Method and apparatus for supporting carrier aggregation in wireless communication system

ABSTRACT

An idle mode measurement method performed by a user equipment (UE) includes receiving measurement configuration information in a radio resource control (RRC) idle mode; performing measurement in the RRC idle mode, based on the measurement configuration information; receiving a UEInformationRequest message for requesting a result of the measurement in the RRC idle mode; and transmitting a UEInformationResponse message including the result of the measurement in the RRC idle mode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2019-0016840, filed on Feb. 13,2019, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to wireless communication systems, and moreparticularly, to a method and apparatus for supporting carrieraggregation.

2. Description of the Related Art

In order to meet the increasing demand with respect to wireless datatraffic after the commercialization of 4G communication systems, effortshave been made to develop improved 5G communication systems or pre-5Gcommunication systems. For this reason, 5G communication systems orpre-5G communication systems are called Beyond 4G network communicationsystems or Post LTE systems. In order to achieve a high datatransmission rate, consideration is given to implementing 5Gcommunication systems in millimeter wave (mmW) frequency bands (e.g., 60GHz bands). In order to reduce propagation path loss and increase apropagation distance in the millimeter wave frequency bands, in 5Gcommunication systems, discussions are underway about technologies suchas beam-forming, massive multiple input multiple output (MIMO), fulldimensional MIMO (FD-MIMO), array antenna, analog beam-forming, andlarge scale antenna. Also, in order to improve networks of systems, in5G communication systems, developments of technologies such as evolvedsmall cell, advanced small cell, cloud radio access network (cloud RAN),ultra-dense network, device to device communication (D2D), wirelessbackhaul, moving network, cooperative communication, coordinatedmulti-points (CoMP), and interference cancellation are underway.Furthermore, in 5G communication systems, developments of an advancedcoding modulation (ACM) scheme such as hybrid FSK and QAM modulation(FQAM) and sliding window superposition coding (SWSC) and an enhancednetwork access scheme such as filter bank multi carrier (FBMC),non-orthogonal multiple access (NOMA), or sparse code multiple access(SCMA) are underway.

The Internet is being developed from a human-centered network via whichpeople generate and consume information to an Internet of Things (IoT)network via which distributed components, such as things, transmit orreceive information to or from each other and process the information.Internet of Everything (IoE) technology in which big data processingtechnology is combined with IoT technology via connection with a cloudserver or the like, is emerging. To implement IoT, technical elements,such as sensing technology, a wired/wireless communication and networkinfrastructure, service interface technology, and security technology,are required, and thus a sensor network, machine to machine (M2M)communication, machine type communication (MTC), and the like forconnection between things have recently been studied. In IoTenvironments, an intelligent Internet Technology (IT) service forcollecting and analyzing data generated by connected things and creatinga new value in people's lives may be provided. IoT is applicable tovarious fields, such as smart home, smart building, smart city, smartcar or connected car, smart grid, health care, smart home appliances,and advanced medical care, via convergence and combination of existinginformation technology (IT) with various industries.

Accordingly, various attempts are made to apply 5G communication systemsto IoT networks. For example, technology such as a sensor network, M2Mcommunication, or MTC is implemented by 5G communication technology suchas beam-forming, MIMO, or array antenna. The application of a cloud RANas big data processing technology may also be considered as an exampleof convergence of 5G technology and IoT technology.

Because mobile communication systems may provide various services due tothe development of the above mobile communication systems, methods ofeffectively providing the services are required.

SUMMARY

Provided is a method and apparatus capable of effectively supportingcarrier aggregation in a mobile communication system.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments of the disclosure.

According to an embodiment of the disclosure, an idle mode measurementmethod performed by a user equipment (UE) includes receiving measurementconfiguration information in a radio resource control (RRC) idle mode;performing measurement in the RRC idle mode, based on the measurementconfiguration information; receiving a UEInformationRequest message forrequesting a result of the measurement in the RRC idle mode; andtransmitting a UEInformationResponse message including the result of themeasurement in the RRC idle mode.

The result of the measurement may include a measurement result of aserving sell and a result of measurement with respect to each of one ormore frequency carriers, and the result of the measurement with respectto each of one or more frequency carriers may include a measurementresult of one or more cells.

The receiving of the measurement configuration information in the RRCidle mode may include receiving measurement configuration informationincluded in an RRCConnectionRelease message or system information.

The system information may include at least one of an indicator(reportQuantities) indicating whether the UE reports the result of themeasurement in the RRC idle mode measurement with reference signalreceived power (RSRP), reference signal received quality (RSRQ), or boththe RSRP and the RSRQ, an indicator (reportQuantityRsIndexes) indicatingwhether the UE reports a measurement result for each reference signal(RS) index in the RRC idle mode with the RSRP or the RSRQ or with bothof the RSRP and the RSRQ, an indicator (maxNrofRS-IndexesToReport)indicating how many measurement results at maximum from among themeasurement results for the RS indexes in the RRC idle mode the UEreports, or an indicator (includeBeamMeasurements) indicating whether toinclude a beam measurement result.

The system information may include at least one of information(nrofSS-BlocksToAverage) about the number of synchronization signalblocks that are used to derive a cell measurement value, a threshold(absThreshSS-BlocsConsolidation) that is used to consolidate measurementvalues of the synchronization signal blocks, measurement timingconfiguration information (smtc), a sub-carrier spacing between thesynchronization signal blocks (ssbSubcarrierSpacing), or timinginformation (deriveSSB-IndexFromCell) that is used to determine indexesof the synchronization signal blocks.

The system information may include at least one of frequency information(measIdleCarrierList) about frequencies that are to be measured in theRRC idle mode by the UE, information (measIdleDuration) about a durationwhile the UE performs measurement, cell list information (measCellList)of a list of cells that are to be measured in the RRC idle mode by theUE, or information (quantityThreshold) about a threshold based on whichthe UE determines whether to report the result of the measurement in theRRC idle mode.

The idle mode measurement method may include transmitting anRRCResumeRequest message; and

receiving an RRCConnectionReject message, wherein, when theRRCConnectionReject message includes waitTime, the UE continuouslyperforms measurement in the RRC idle mode until a timer operatingaccording to the information (measIdleDuration) expires.

According to another embodiment of the disclosure, an idle modemeasurement supporting method performed by a base station includesreceiving measurement configuration information in an RRC idle modethrough an RRCConnectionRelease message or system information; receivinga UEInformationRequest message for requesting a result of measurement inthe RRC idle mode; and receiving a UEInformationResponse messageincluding the result of the measurement in the RRC idle mode.

The system information may include at least one of an indicator(reportQuantities) indicating whether the UE reports the result of themeasurement in the RRC idle mode measurement with reference signalreceived power (RSRP), reference signal received quality (RSRQ), or boththe RSRP and the RSRQ, an indicator (reportQuantityRsIndexes) indicatingwhether the UE reports a measurement result for each reference signal(RS) index in the RRC idle mode with the RSRP or the RSRQ or with bothof the RSRP and the RSRQ, an indicator (maxNrofRS-IndexesToReport)indicating how many measurement results at maximum from among themeasurement results for the RS indexes in the RRC idle mode the UEreports, or an indicator (includeBeamMeasurements) indicating whether toinclude a beam measurement result.

The system information may include at least one of information(nrofSS-BlocksToAverage) about the number of synchronization signalblocks that are used to derive a cell measurement value, a threshold(absThreshSS-BlocsConsolidation) that is used to consolidate measurementvalues of the synchronization signal blocks, measurement timingconfiguration information (smtc), a sub-carrier spacing between thesynchronization signal blocks (ssbSubcarrierSpacing), or timinginformation (deriveSSB-IndexFromCell) that is used to determine indexesof the synchronization signal blocks.

According to another embodiment of the disclosure, a UE for performingmeasurement in an RRC idle mode includes a transceiver; and a processorcoupled to the transceiver and configured to receive measurementconfiguration information, to perform measurement, based on themeasurement configuration information, to receive a UEInformationRequestmessage for requesting a result of the measurement, and to transmit aUEInformationResponse message including the result of the measurement.

The result of the measurement may include a measurement result of aserving sell and a result of measurement with respect to each of one ormore frequency carriers, and the result of the measurement with respectto each of one or more frequency carriers may include a measurementresult of one or more cells.

The processor may be further configured to receive measurementconfiguration information included in an RRCConnectionRelease message orsystem information.

The system information may include at least one of an indicator(reportQuantities) indicating whether the UE reports the result of themeasurement in the RRC idle mode measurement with reference signalreceived power (RSRP), reference signal received quality (RSRQ), or boththe RSRP and the RSRQ, an indicator (reportQuantityRsIndexes) indicatingwhether the UE reports a measurement result for each reference signal(RS) index in the RRC idle mode with the RSRP or the RSRQ or with bothof the RSRP and the RSRQ, an indicator (maxNrofRS-IndexesToReport)indicating how many measurement results at maximum from among themeasurement results for the RS indexes in the RRC idle mode the UEreports, or an indicator (includeBeamMeasurements) indicating whether toinclude a beam measurement result.

The system information may include at least one of information(nrofSS-BlocksToAverage) about the number of synchronization signalblocks that are used to derive a cell measurement value, a threshold(absThreshSS-BlocsConsolidation) that is used to consolidate measurementvalues of the synchronization signal blocks, measurement timingconfiguration information (smtc), a sub-carrier spacing between thesynchronization signal blocks (ssbSubcarrierSpacing), or timinginformation (deriveSSB-IndexFromCell) that is used to determine indexesof the synchronization signal blocks.

The system information may include at least one of frequency information(measIdleCarrierList) about frequencies that are to be measured in theRRC idle mode by the UE, information (measIdleDuration) about a durationwhile the UE performs measurement, cell list information (measCellList)of a list of cells that are to be measured in the RRC idle mode by theUE, or information (quantityThreshold) about a threshold based on whichthe UE determines whether to report the result of the measurement in theRRC idle mode.

The processor may be further configured to transmit an RRCResumeRequestmessage and receive an RRCConnectionReject message, and, when theRRCConnectionReject message includes waitTime, the UE may continuouslyperform measurement in the RRC idle mode until a timer operatingaccording to the information (measIdleDuration) expires.

According to another embodiment of the disclosure, a base station forsupporting idle mode measurement includes a transceiver; and a processorcoupled to the transceiver and configured to transmit measurementconfiguration information in an RRC idle mode through anRRCConnectionRelease message or system information, to transmit aUEInformationRequest message for requesting a result of measurement inthe RRC idle mode, and to receive a UEInformationResponse messageincluding the result of the measurement in the RRC idle mode.

The system information may include at least one of an indicator(reportQuantities) indicating whether the UE reports the result of themeasurement in the RRC idle mode measurement with reference signalreceived power (RSRP), reference signal received quality (RSRQ), or boththe RSRP and the RSRQ, an indicator (reportQuantityRsIndexes) indicatingwhether the UE reports a measurement result for each reference signal(RS) index in the RRC idle mode with the RSRP or the RSRQ or with bothof the RSRP and the RSRQ, an indicator (maxNrofRS-IndexesToReport)indicating how many measurement results at maximum from among themeasurement results for the RS indexes in the RRC idle mode the UEreports, or an indicator (includeBeamMeasurements) indicating whether toinclude a beam measurement result.

The system information may include at least one of information(nrofSS-BlocksToAverage) about the number of synchronization signalblocks that are used to derive a cell measurement value, a threshold(absThreshSS-BlocsConsolidation) that is used to consolidate measurementvalues of the synchronization signal blocks, measurement timingconfiguration information (smtc), a sub-carrier spacing between thesynchronization signal blocks (ssbSubcarrierSpacing), or timinginformation (deriveSSB-IndexFromCell) that is used to determine indexesof the synchronization signal blocks.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A illustrates a diagram of a structure of a Long Term Evolution(LTE) system according to an embodiment of the disclosure;

FIG. 1B illustrates a diagram of a radio protocol architecture in an LTEsystem, according to an embodiment of the disclosure;

FIG. 1C illustrates a diagram of a structure of a next-generation mobilecommunication system, according to an embodiment of the disclosure;

FIG. 1D illustrates a diagram of a radio protocol architecture of anext-generation mobile communication system, according to an embodimentof the disclosure;

FIG. 1E illustrates a diagram for describing a procedure in which a userequipment (UE) not supporting idle mode measurement switches from aradio resource control (RRC) idle mode to an RRC connected mode, and aprocedure in which a base station configures carrier aggregation (CA)for the UE, according to an embodiment of the disclosure;

FIG. 1F illustrates a diagram for describing a procedure in which a UEsupporting idle mode measurement performs the idle mode measurement anda base station configures CA for the UE, according to an embodiment ofthe disclosure;

FIG. 1G illustrates a diagram for describing a procedure in which a UEperforms the idle mode measurement and a base station configures CA forthe UE, according to an embodiment of the disclosure;

FIG. 1H illustrates a diagram for describing a procedure in which a UEperforms the idle mode measurement and a base station configures CA forthe UE, according to an embodiment of the disclosure;

FIG. 1I illustrates a block diagram of a structure of a UE according toan embodiment of the disclosure;

FIG. 1J illustrates a block diagram of a structure of a base stationaccording to an embodiment of the disclosure;

FIG. 2A illustrates a diagram of a structure of an LTE system accordingto an embodiment of the disclosure;

FIG. 2B illustrates a diagram of a radio protocol architecture in an LTEsystem, according to an embodiment of the disclosure;

FIG. 2C illustrates a diagram of a structure of a next-generation mobilecommunication system, according to an embodiment of the disclosure;

FIG. 2D illustrates a diagram of a radio protocol architecture of anext-generation mobile communication system, according to an embodimentof the disclosure;

FIG. 2E illustrates a diagram for describing a procedure in which a UEnot supporting idle mode measurement switches from an RRC idle mode toan RRC connected mode, and a procedure in which a base stationconfigures CA for the UE, according to an embodiment of the disclosure;

FIG. 2F illustrates a diagram for describing a procedure in which a UEnot supporting idle mode measurement switches from an RRC inactive modeto an RRC connected mode, and a procedure in which a base stationconfigures CA for the UE, according to an embodiment of the disclosure;

FIG. 2G illustrates a diagram for describing a procedure in which a UEsupporting idle mode measurement switches from an RRC connected mode toan RRC idle mode, and a method in which a base station provides idlemode measurement configuration information to the UE, according to anembodiment of the disclosure;

FIG. 2H illustrates a diagram for describing a procedure in which a UEsupporting idle mode measurement switches from an RRC connected mode toan RRC inactive mode, and a method in which a base station provides idlemode measurement configuration information to the UE, according to anembodiment of the disclosure;

FIG. 2I illustrates a block diagram of a structure of a UE according toan embodiment of the disclosure; and

FIG. 2J illustrates a block diagram of a structure of a base stationaccording to an embodiment of the disclosure.

DETAILED DESCRIPTION

FIGS. 1A through 2J, discussed below, and the various embodiments usedto describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

Throughout the disclosure, the expression “at least one of a, b or c”indicates only a, only b, only c, both a and b, both a and c, both b andc, all of a, b, and c, or variations thereof.

Examples of a terminal may include a user equipment (UE), a mobilestation (MS), a cellular phone, a smartphone, a computer, and amultimedia system capable of performing a communication function.

In the disclosure, a controller may also be referred to as a processor.

In the disclosure, a layer may also be referred to as an entity.

Operation principles of the disclosure will now be described more fullywith reference to the accompanying drawings. While describing thedisclosure, detailed description of related well-known functions orconfigurations may be omitted when it is deemed that they mayunnecessarily obscure the essence of the disclosure. Also, terms usedbelow are defined in consideration of functions in the disclosure, andmay have different meanings according to an intention of a user oroperator, customs, or the like. Thus, the terms should be defined basedon the description throughout the specification.

For the same reason, some elements in the drawings are exaggerated,omitted, or schematically illustrated. Also, actual sizes of respectiveelements are not necessarily represented in the drawings. In thedrawings, the same or corresponding elements are denoted by the samereference numerals.

The advantages and features of the disclosure and methods of achievingthe advantages and features will become apparent with reference toembodiments of the disclosure described in detail below with referenceto the accompanying drawings. The disclosure may, however, be embodiedin many different forms and should not be construed as being limited tothe embodiments set forth herein; rather, these embodiments are providedso that this disclosure will be thorough and complete, and will fullyconvey the concept of the disclosure to those skilled in the art. Thescope of the disclosure is only defined in the claims. Throughout thespecification, like reference numerals or characters refer to likeelements.

It will be understood that each block of flowchart illustrations andcombinations of blocks in the flowchart illustrations may be implementedby computer program instructions. These computer program instructionsmay be provided to a processor of a general-purpose computer, specialpurpose computer, or other programmable data processing equipment, suchthat the instructions, which are executed via the processor of thecomputer or other programmable data processing equipment, generate meansfor performing functions specified in the flowchart block(s). Thesecomputer program instructions may also be stored in a computer-usable orcomputer-readable memory that may direct a computer or otherprogrammable data processing equipment to function in a particularmanner, such that the instructions stored in the computer-usable orcomputer-readable memory produce a manufactured article includinginstruction means that perform the functions specified in the flowchartblock(s). The computer program instructions may also be loaded onto acomputer or other programmable data processing equipment to cause aseries of operational steps to be performed on the computer or otherprogrammable data processing equipment to produce a computer-executableprocess such that the instructions that are executed on the computer orother programmable data processing equipment provide steps forimplementing the functions specified in the flowchart block or blocks.

In addition, each block may represent a module, segment, or portion ofcode, which includes one or more executable instructions forimplementing specified logical function(s). It should also be noted thatin some alternative implementations, the functions noted in the blocksmay occur out of the presented order. For example, two blocks shown insuccession may in fact be executed substantially concurrently or theblocks may sometimes be executed in the reverse order, according to thefunctionality involved.

The term “unit” or ‘˜er(or)’ used herein denotes a software element or ahardware element such as a field-programmable gate array (FPGA) or anapplication-specific integrated circuit (ASIC), and performs a certainfunction. However, the term ‘unit’ or ‘˜er(or)’ is not limited tosoftware or hardware. The term ‘unit’ or ‘˜er(or)’ may be configured tobe included in an addressable storage medium or to reproduce one or moreprocessors. Thus, the term ‘unit’ or ‘˜er(or)’ may include, by way ofexample, object-oriented software components, class components, and taskcomponents, and processes, functions, attributes, procedures,subroutines, segments of a program code, drivers, firmware, a microcode, a circuit, data, a database, data structures, tables, arrays, andvariables. Functions provided by components and ‘units’ or ‘˜ers(ors)’may be combined into a smaller number of components and ‘units’ or‘˜ers(ors)’ or may be further separated into additional components and‘units’ or ‘˜ers(ors)’. In addition, the components and ‘units’ or‘˜ers(ors)’ may be implemented to operate one or more central processingunits (CPUs) in a device or a secure multimedia card. According to anembodiment of the disclosure, the ‘unit’ or ‘˜er(or)’ may include one ormore processors.

While describing the disclosure, detailed description of relatedwell-known functions or configurations may be omitted when it is deemedthat they may unnecessarily obscure the essence of the disclosure.Embodiments of the disclosure will now be described more fully withreference to the accompanying drawings, in which exemplary embodimentsare shown.

As used in the following description, terms identifying access nodes,terms indicating network entities, terms indicating messages, termsindicating interfaces between network entities, terms indicating varioustypes of identification information, etc. are exemplified forconvenience of explanation. Accordingly, the disclosure is not limitedto terms to be described later, and other terms representing objectshaving the equivalent technical meaning may be used.

Hereinafter, for convenience of description, the disclosure uses termsand names defined in the 3rd Generation Partnership Project Long TermEvolution (3GPP LTE) standard. However, the disclosure is not limited tothe terms and names but may also be identically applied to systems thatcomply with other standards. In the disclosure, eNB may be usedinterchangeably with gNB for convenience of explanation. In other words,a base station described as an eNB may also indicate a gNB.

Hereinafter, a base station is a subject that performs resourceallocation of a terminal, and may be at least one of gNode B, eNode B,Node B, base station (BS), a radio access unit, a base stationcontroller, or a node on a network. Examples of a terminal may include auser equipment (UE), a mobile station (MS), a cellular phone, asmartphone, a computer, and a multimedia system capable of performing acommunication function. Of course, embodiments of the disclosure are notlimited thereto.

In particular, the disclosure may be applied to the 3GPP New Radio (NR)(5^(th) mobile communications standard). The disclosure is applicable tointelligent services based on the 5G communication technology and theInternet of Things (IoT) related technology (e.g., smart home, smartbuilding, smart city, smart car or connected car, health care, digitaleducation, retail business, and security- and safety-related service).In the disclosure, eNB may be used interchangeably with gNB forconvenience of explanation. In other words, a base station described asan eNB may also indicate a gNB. Furthermore, the term ‘terminal’ mayrefer to a mobile phone, NB-IoT devices, sensors, and other wirelesscommunication devices.

A wireless communication system has evolved from an initial one thatprovides a voice-oriented service to a broadband wireless communicationsystem that provides a high-speed and high-quality packet data service,like the communication standards, such as 3GPP high speed packet access(HSPA), LTE or Evolved Universal Terrestrial Radio Access (E-UTRA),LTE-Advanced (LTE-A), LTE-Pro, 3GPP2 high rate packet data (HRPD), UltraMobile Broadband (UMB), the Institute of Electrical and ElectronicsEngineers (IEEE) 802.16e, etc.

In an LTE system as a representative example of a broadband wirelesscommunication system, orthogonal frequency division multiplexing (OFDM)is employed in a downlink (DL) and single carrier frequency divisionmultiple access (SC-FDMA) is employed in an uplink (UL). The UL means aradio link through which a UE transmits data or a control signal to abase station (eNodeB or BS), and the DL means a radio link through whichthe base station transmits data or a control signal to the UE. Theabove-described multiple access scheme separates data or controlinformation for each user by allocating and operating time-frequencyresources on which the data or the control information is carried foreach user, so that the time-frequency resources do not overlap eachother, that is, so that orthogonality is realized.

A 5G communication system, that is, a post-LTE communication system,needs to freely reflect various requirements from a user and a serviceprovider, such that a service satisfying the various requirements at thesame time has to be supported. Services taken into consideration for the5G communication system may include enhanced mobile broadband (eMBB)communication, massive machine type communication (mMTC), ultrareliability low latency communication (URLLC), etc.

According to an embodiment, the eMBB may aim to provide a furtherenhanced data transmission speed than a data transmission speedsupported by existing LTE, LTE-A, or LTE-Pro. For example, in the 5Gcommunication system, with respect to one BS, the eMBB needs to providea peak data rate of 20 Gbps in the DL and a peak data rate of 10 Gbps inthe UL. Furthermore, the 5G communication system should be able toprovide an increased user-perceived data rate while providing the peakdata rate. In order to satisfy such a requirement, various transmissionand reception technologies including a further enhanced MIMOtransmission technology must be improved. Moreover, the LTE systemtransmits a signal using a 20 MHz maximum transmission bandwidth in the2 GHz band, whereas the 5G communication system transmits a signal usinga frequency bandwidth wider than 20 MHz in a frequency band of 3 to 6GHz or more, thus satisfying the data rates required for the 5Gcommunication system.

In the 5G communication system, mMTC is taken into consideration inorder to support application services, such as IoT. Access by many UEswithin a single cell, coverage improvement of a UE, an increased batterytime, a reduction in the cost of a UE are required in order for mMTC toefficiently provide for the IoT. The IoT is attached to various sensorsand various devices to provide a communication function, and thus shouldbe able to support many UEs (e.g., 1,000,000 UEs/km2) within a cell.Furthermore, a UE supporting mMTC requires wider coverage compared toother services provided by the 5G communication system because there isa high possibility that the UE may be located in a shadow area notcovered by a cell, such as the underground of a building. A UEsupporting mMTC needs to be a cheap UE, and requires a very long batterylife time, such as 10 to 15 years, because it is difficult to frequentlyreplace the battery of the UE.

Last, URLLC is a mission-critical cellular-based wireless communicationservice, and may be used for services used for remote control of robotsor machinery, industrial automation, unmanned aerial vehicles, remotehealth care, emergency alert, etc. Accordingly, communication providedby URLLC should be very low latency and very high reliability. Forexample, services supporting URLLC may require air interface latency tobe less than 0.5 millisecond and also a packet error rate of 10⁻⁵ orless. Accordingly, for services supporting URLLC, the 5G system needs toprovide a transmission time interval (TTI) less than that of otherservices, and also requires the design for allocating resources in awide frequency band in order to secure reliability of a communicationlink.

Three services of the above-described 5G system, that is, eMBB, URLLC,and mMTC, may be multiplexed and transmitted in one system. In order tosatisfy different requirements of the services, different transmissionand reception schemes and parameters may be used between the services.However, the above-described mMTC, URLLC, and eMBB are merely examplesof different service types, and a service type to which the disclosureis applied is not limited to the foregoing examples.

Although embodiments of the disclosure are hereinafter described withrespect to an LTE, LTE-Advanced (LTE-A), LTE Pro, or 5G (or NR asnext-generation mobile communication) system, the embodiments of thedisclosure may be applied to other communication systems having similartechnical backgrounds and channel configurations. Furthermore, it shouldbe understood by those skilled in the art that the embodiments of thedisclosure are applicable to other communication systems thoughmodifications not departing from the scope of the disclosure.

FIG. 1A illustrates a diagram of a structure of an LTE system accordingto an embodiment of the disclosure.

Referring to FIG. 1A, a radio access network (RAN) of the LTE systemincludes evolved node Bs (hereinafter, referred to as eNBs, node Bs(NBs) or base stations) 1 a-05, 1 a-10, 1 a-15, and 1 a-20, a mobilitymanagement entity (MME) 1 a-25, and a serving-gateway (S-GW) 1 a-30. Auser equipment (UE) 1 a-35 (also referred to as a terminal) may accessan external network via the eNB 1 a-05, 1 a-10, 1 a-15, or 1 a-20 andthe S-GW 1 a-30.

In FIG. 1A, the eNB 1 a-05, 1 a-10, 1 a-15, or 1 a-20 may correspond toan existing NB of a universal mobile telecommunication system (UMTS).The eNB 1 a-05, 1 a-10, 1 a-15, or 1 a-20 may be connected to the UE 1a-35 through a radio channel and may perform complex functions comparedto the existing NB. In the LTE system, all user traffic including areal-time service such as voice over internet protocol (VoIP) may beprovided via a shared channel. Accordingly, an entity that schedules UEs1 a-35 by gathering state information such as buffer states, availabletransmit power states, and channel states of the UEs 1 a-35 may benecessary, and the eNB 1 a-05, 1 a-10, 1 a-15, or 1 a-20 may operate asthe entity.

A single eNB may generally control multiple cells. For example, the LTEsystem may use radio access technology such as orthogonal frequencydivision multiplexing (OFDM) at a bandwidth of 20 MHz to achieve a datarate of 100 Mbps. Also, the eNB 1 a-05, 1 a-10, 1 a-15, or 1 a-20 mayuse an adaptive modulation and coding (AMC) scheme to determine amodulation scheme and a channel coding rate in accordance with a channelstate of the UE 1 a-35. The S-GW 1 a-30 is an entity for providing databearers and may configure or release the data bearers under the controlof the MME 1 a-25. The MME 1 a-25 is an entity for performing a mobilitymanagement function and various control functions for the UE 1 a-35 andmay be connected to the eNBs 1 a-05, 1 a-10, 1 a-15, and 1 a-20.

FIG. 1B illustrates a diagram of a radio protocol architecture in an LTEsystem, according to an embodiment of the disclosure.

Referring to FIG. 1B, the radio protocol architecture of the LTE systemmay include packet data convergence protocol (PDCP) layers 1 b-05 and 1b-40, radio link control (RLC) layers 1 b-10 and 1 b-35, and mediaaccess control (MAC) layers 1 b-15 and 1 b-30 respectively for a UE andan eNB. The PDCP layer 1 b-05 or 1 b-40 is in charge of IP headercompression/decompression, etc. Main functions of the PDCP layer 1 b-05or 1 b-40 may be summarized as below. Embodiments of the disclosure arenot limited to the following functions.

-   -   Header compression and decompression: ROHC only    -   Transfer of user data    -   In-sequence delivery of upper layer PDUs at PDCP        re-establishment procedure for RLC AM    -   For split bearers in DC (only support for RLC AM): PDCP PDU        routing for transmission and PDCP PDU reordering for reception    -   Duplicate detection of lower layer SDUs at PDCP re-establishment        procedure for RLC AM    -   Retransmission of PDCP SDUs at handover and, for split bearers        in DC, of PDCP PDUs at PDCP data-recovery procedure, for RLC AM    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

The RLC layer 1 b-10 or 1 b-35 may perform, for example, an automaticrepeat request (ARQ) operation by reconfiguring PDCP PDUs to appropriatesizes. Main functions of the RLC layer 1 b-10 or 1 b-35 may besummarized as below. Embodiments of the disclosure are not limited tothe following functions.

-   -   Transfer of upper layer PDUs    -   Error Correction through ARQ (only for AM data transfer)    -   Concatenation, segmentation and reassembly of RLC SDUs (only for        UM and AM data transfer)    -   Re-segmentation of RLC data PDUs (only for AM data transfer)    -   Reordering of RLC data PDUs (only for UM and AM data transfer)    -   Duplicate detection (only for UM and AM data transfer)    -   Protocol error detection (only for AM data transfer)    -   RLC SDU discard (only for UM and AM data transfer)    -   RLC re-establishment

The MAC layer 1 b-15 or 1 b-30 is connected to multiple RLC layersconfigured for a single UE and may multiplex RLC PDUs into a MAC PDU anddemultiplex the RLC PDUs from the MAC PDU. Main functions of the MAClayer 1 b-15 or 1 b-30 may be summarized as below. Embodiments of thedisclosure are not limited to the following functions.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs belonging to one or        different logical channels into/from transport blocks (TB)        delivered to/from the physical layer on transport channels    -   Scheduling information reporting    -   Error correction through HARQ    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification    -   Transport format selection    -   Padding

A physical (PHY) layer 1 b-20 or 1 b-25 may channel-code and modulateupper layer data into OFDM symbols and transmit the OFDM symbols througha radio channel, or demodulate OFDM symbols received through a radiochannel and channel-decode and deliver the OFDM symbols to an upperlayer. Embodiments of the disclosure are not limited thereto.

FIG. 1C illustrates a diagram of a structure of a next-generation mobilecommunication system, according to an embodiment of the disclosure.

Referring to FIG. 1C, a RAN of the next-generation mobile communicationsystem (e.g., a new radio (NR) or 5G system) may include a new radionode B (hereinafter, referred to as a NR gNB or an NR base station) 1c-10 and a new radio core network (NR CN) 1 c-05. A new radio userequipment (NR UE) or UE 1 c-15 may access an external network via the NRgNB 1 c-10 and the NR CN 1 c-05.

In FIG. 1C, the NR gNB 1 c-10 may correspond to an eNB of an existingLTE system. The NR gNB 1 c-10 is connected to the NR UE 1 c-15 throughradio channels and may provide superior services compared to an existingNB. In the next-generation mobile communication system, all user trafficmay be provided via a shared channel. Accordingly, an entity thatschedules UEs by gathering state information such as buffer states,available transmit power states, and channel states of the UEs may benecessary, and the NR gNB 1 c-10 may operate as the entity. A single NRgNB may generally control multiple cells. In the next-generation mobilecommunication system, a bandwidth greater than a current maximumbandwidth may be used to achieve an ultrahigh data rate compared to acurrent LTE system. OFDM may be used as radio access technology, andbeamforming technology may be additionally used. According to anembodiment, the NR gNB 1 c-10 may use an AMC scheme to determine amodulation scheme and a channel coding rate in accordance with a channelstate of the UE.

The NR CN 1 c-05 may perform functions such as mobility support, bearersetup, and quality of service (QoS) setup. The NR CN 1 c-05 is an entityfor performing a mobility management function and various controlfunctions for the UE may be connected to multiple NR gNBs 1 c-10. Thenext-generation mobile communication system may cooperate with theexisting LTE system, and the NR CN 1 c-05 may be connected to an MME 1c-25 through a network interface. The MME 1 c-25 may be connected to aneNB 1 c-30 being an existing base station.

FIG. 1D illustrates a diagram of a radio protocol architecture of anext-generation mobile communication system, according to an embodimentof the disclosure.

Referring to FIG. 1D, the radio protocol architecture of thenext-generation mobile communication system may include NR service dataadaptation protocol (SDAP) layers 1 d-01 and 1 d-45, NR PDCP layers 1d-05 and 1 d-40, NR RLC layers 1 d-10 and 1 d-35, NR MAC layers 1 d-15and 1 d-30, and NR PHY layers 1 d-20 and 1 d-25 respectively for a UEand an NR gNB.

According to an embodiment, main functions of the NR SDAP layer 1 d-01or 1 d-45 may include some of the following functions. Embodiments ofthe disclosure are not limited to the following functions.

-   -   Transfer of user plane data    -   Mapping between a QoS flow and a DRB for both DL and UL    -   Marking QoS flow ID in both DL and UL packets    -   Reflective QoS flow to DRB mapping for the UL SDAP PDUs

With respect to an SDAP layer, the UE may receive, via a radio resourcecontrol (RRC) message, settings on whether to use a header of the SDAPlayer or use a function of the SDAP layer for each PDCP layer, eachbearer, or each logical channel. When an SDAP header is configured, theUE may instruct a non-access stratum (NAS) reflective QoS 1-bitindicator and an access stratum (AS) reflective QoS 1-bit indicator ofthe SDAP header to update or reconfigure mapping information regardingthe data bearer and the QoS flow of uplink (UL) and downlink (DL). TheSDAP header may include QoS flow ID indicating QoS. According to anembodiment, QoS information may be used as data processing priorityinformation, scheduling information, etc. for supporting a smoothservice.

According to an embodiment, main functions of the NR PDCP layer 1 d-05or 1 d-40 may include some of the following functions. Embodiments ofthe disclosure are not limited to the following functions.

-   -   Header compression and decompression: ROHC only    -   Transfer of user data    -   In-sequence delivery of upper layer PDUs    -   Out-of-sequence delivery of upper layer PDUs    -   PDCP PDU reordering for reception    -   Duplicate detection of lower layer SDUs    -   Retransmission of PDCP SDUs    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

According to an embodiment, a reordering function of the NR PDCP layer 1d-05 or 1 d-40 may denote a function of reordering PDCP PDUs receivedfrom a lower layer, based on a PDCP sequence number (SN). The reorderingfunction of the NR PDCP layer 1 d-05 or 1 d-40 may include at least oneof a function of delivering the reordered data to an upper layer inorder, a function of immediately delivering the reordered data withoutconsidering an order, a function of recording missing PDCP PDUs byreordering the PDCP PDUs, a function of reporting a status of themissing PDCP PDUs to a transmitter, or a function of requesting toretransmit the missing PDCP PDUs.

According to an embodiment, main functions of the NR RLC layer 1 d-10 or1 d-35 may include some of the following functions. Embodiments of thedisclosure are not limited to the following functions.

-   -   Transfer of upper layer PDUs    -   In-sequence delivery of upper layer PDUs    -   Out-of-sequence delivery of upper layer PDUs    -   Error Correction through ARQ    -   Concatenation, segmentation and reassembly of RLC SDUs    -   Re-segmentation of RLC data PDUs    -   Reordering of RLC data PDUs    -   Duplicate detection    -   Protocol error detection    -   RLC SDU discard    -   RLC re-establishment

According to an embodiment, in-sequence delivery of the NR RLC layer 1d-10 or 1 d-35) may denote a function of delivering RLC SDUs receivedfrom a lower layer, to an upper layer in order. When an RLC SDU issegmented into multiple RLC SDUs and received, the in-sequence deliveryof the NR RLC layer 1 d-10 or 1 d-35 may include a function ofreassembling the multiple RLC SDUs and delivering the RLC SDUs.

The in-sequence delivery of the NR RLC layer 1 d-10 or 1 d-35 mayinclude at least one of a function of reordering received RLC PDUs on anRLC SN or PDCP SN basis, a function of recording missing RLC PDUs byreordering the RLC PDUs, a function of reporting a status of the missingRLC PDUs to a transmitter, or a function of requesting to retransmit themissing RLC PDUs.

According to an embodiment, the in-sequence delivery of the NR RLC layer1 d-10 or 1 d-35 may include a function of delivering only RLC SDUsprevious to a missing RLC SDU, to the upper layer in order, when themissing RLC SDU exists. According to an embodiment, the in-sequencedelivery of the NR RLC layer 1 d-10 or 1 d-35 may include a function ofdelivering all RLC SDUs received before a timer is started, to the upperlayer in order, when a certain timer is expired although a missing RLCSDU exists. The in-sequence delivery of the NR RLC layer 1 d-10 or 1d-35 may include a function of delivering all RLC SDUs received up to acurrent time, to the upper layer in order, when a certain timer isexpired although a missing RLC SDU exists. Embodiments of the disclosureare not limited thereto.

According to an embodiment, the NR RLC layer 1 d-10 or 1 d-35 mayprocess the RLC PDUs in order of reception regardless of sequencenumbers and deliver the RLC PDUs to the NR PDCP layer 1 d-05 or 1 d-40(out-of sequence delivery).

According to an embodiment, when the NR RLC layer 1 d-10 or 1 d-35receives segments, the NR RLC layer 1 d-10 or 1 d-35 may reconfigure thesegments received later or stored in a buffer, into a whole RLC PDU anddeliver the whole RLC PDU to the NR PDCP layer 1 d-05 or 1 d-40.According to an embodiment, the NR RLC layer 1 d-10 or 1 d-35 may nothave a concatenation function, and the concatenation function may beperformed by the NR MAC layer 1 d-15 or 1 d-30 or be replaced with amultiplexing function of the NR MAC layer 1 d-15 or 1 d-30.

According to an embodiment, out-of-sequence delivery of the NR RLC layer1 d-10 or 1 d-35 may denote a function of delivering RLC SDUs receivedfrom a lower layer, immediately to an upper layer out of an order. Theout-of-sequence delivery of the NR RLC layer 1 d-10 or 1 d-35 mayinclude a function of reassembling multiple RLC SDUs segmented from anRLC SDU and delivering the RLC SDU when the segmented RLC SDUs arereceived. The out-of-sequence delivery of the NR RLC layer 1 d-10 or 1d-35 may include a function of storing RLC SNs or PDCP SNs of receivedRLC PDUs and recording missing RLC PDUs by ordering the RLC PDUs.

According to an embodiment, the NR MAC layer 1 d-15 or 1 d-30 may beconnected to multiple NR RLC layers 1 d-10 or 1 d-35 configured for asingle UE, and main functions of the NR MAC layer 1 d-15 or 1 d-30 mayinclude some of the following functions. Embodiments of the disclosureare not limited to the following functions.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs    -   Scheduling information reporting    -   Error correction through HARQ    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification    -   Transport format selection    -   Padding

According to an embodiment, the NR PHY layer 1 d-20 or 1 d-25 maychannel-code and modulate upper layer data into OFDM symbols andtransmit the OFDM symbols through a radio channel, or demodulate OFDMsymbols received through a radio channel and channel-decode and deliverthe OFDM symbols to an upper layer. However, embodiments of thedisclosure are not limited thereto.

FIG. 1E illustrates a diagram for describing a procedure in which a UEnot supporting an idle mode measurement establishes an RRC connectionwith an eNB/gNB and switches an RRC idle mode to an RRC connected mode,and a procedure in which the eNB/gNB configures carrier aggregation(hereinafter, CA) in the UE, according to an embodiment of thedisclosure.

The UE according to an embodiment of the disclosure may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in the RRC idle mode. However, the UE does not report, to theeNB/gNB, results of measuring one or more frequencies in the RRC idlemode, separately. In other words, after the UE transits from the RRCidle mode to the RRC connected mode, the UE may measure one or morefrequencies, based on measurement configuration information(hereinafter, measConfig) set in an RRCConnectionReconfigurationmessage, and, when a set condition is satisfied, may transmit aMeasurementReport message to the eNB/gNB.

Referring to FIG. 1E, a UE 1 e-01 may be in the RRC idle mode for acertain reason (operation 1 e-03). The UE 1 e-01 in the RRC idle modemay receive system information by searching for and camping on asuitable cell, via a cell selection procedure and/or a cell reselectionprocedure (operation 1 e-05).

The UE 1 e-01 may trigger a random access in order to establish an RRCconnection with an eNB/gNB 1 e-02 (1 e-06). When the random access istriggered, the UE 1 e-01 may select a PRACH occasion and transmit aRandom Access Preamble to the eNB/gNB 1 e-02 (operation 1 e-10). Inresponse to the Random Access Preamble, the eNB/gNB 1 e-02 may transmita Random Access Response (RAR) message to the UE 1 e-01 (operation 1e-15). The UE 1 e-01 in the RRC idle mode may establish an inversedirection transmission synchronization with the eNB/gNB 1 e-02 throughoperations 1 e-10 and 1 e-15.

The UE 1 e-01 in the RRC idle mode that has established an inversedirection transmission synchronization may perform an RRC connectionestablishment procedure with the eNB/gNB 1 e-02. First, the UE 1 e-01may transmit a RRCConnectionRequest message to the eNB/gNB 1 e-02(operation 1 e-20). The RRCConnectionRequest message may include anidentity of the UE 1 e-01, an establishment cause for establishing anRCC connection, or the like. In response to the RRCConnectionRequestmessage, the eNB/gNB 1 e-02 may transmit an RRCConnectionSetup messageto the UE 1 e-01 (operation 1 e-25). The RRCConnectionSetup message mayinclude radio resource setup information (RadioResourceConfigDedicated,radioBearerConfig, or masterCellGroup). In response to theRRCConnectionSetup message, the UE 1 e-01 may set the radio resourcesetup information and may switch the RRC idle mode to the RRC connectedmode (operation 1 e-26). RRC connection establishment may be accompaniedby connection of signaling radio bearer1 (SRB1). Accordingly, an RRCmessage or an RRC message including a NAS message or an initial NASmessage that is a control message between a UE and a BS may betransmitted and received via SRB1. The UE 1 e-01 in the RRC connectedmode may transmit a RRCConnectionSetupComplete message to the eNB/gNB 1e-02 through SRB1 (operation 1 e-30). The RRCConnectionSetupCompletemessage may include a service request message transmitted by the UE 1e-01 to request an access mobility management function (AMF) or MME forbearer configuration for a certain service.

When the RRC connection establishment procedure is successfullyperformed, the eNB/gNB 1 e-02 may perform an RRC connectionreconfiguration procedure with the UE 1 e-01. First, the eNB/gNB 1 e-02may transmit an RRCConnectionReconfiguration message to the UE 1 e-01(operation 1 e-40). The RRCConnectionReconfiguration message may includeat least one of configuration information about a data radio bearer(DRB) to process user data, configuration information about SRB1 and/orSRB2 via which a control message may be transmitted and received, ormeasurement configuration information (measConfig). In response to theRRCConnectionReconfiguration message, the UE 1 e-01 may apply theinformation included in the RRCConnectionReconfiguration message, andthen may transmit an RRCConnectionReconfigurationComplete message to theeNB/gNB 1 e-02 (operation 1 e-45).

When the RRCConnectionReconfiguration message includes the measConfig inoperation 1 e-40, the UE 1 e-01 in the RRC connected mode may performmeasurement by applying the measConfig. When measurement reporting istriggered (operation 1 e-46), the UE 1 e-01 may transmit aMeasurementReport message to the eNB/gNB 1 e-02 (operation 1 e-50).

When the eNB/gNB 1 e-02 successfully receives the MeasurementReportmessage, the eNB/gNB 1 e-02 may perform an RRC connectionreconfiguration procedure to configure CA for the UE 1 e-01 in the RRCconnected mode. CA according to an embodiment of the disclosure meansmore transmitting and receiving data between a UE and a BS through anadditional carrier or secondary cells or serving cells (SCells). First,the eNB/gNB 1 e-02 may transmit an RRCConnectionReconfiguration messageto the UE 1 e-01 (operation 1 e-55). The RRCConnectionReconfigurationmessage may include configuration information (Scell configuration)about at least one SCell. For example, the Scell configuration mayinclude a list of SCells to be added or modified (sCellToAddModList)and/or a list of configured SCells to be released (sCellToReleaseList),each of which is an information element (IE). When the UE 1 e-01successfully receives the RRCConnectionReconfiguration message, the UE 1e-01 may apply the Scell configuration and then transmit anRRCConnectionReconfigurationComplete message to the eNB/gNB 1 e-02(operation 1 e-60). The eNB/gNB 1 e-02 may apply a CA by indicating astate (activated or deactivated state) of each SCell configured in theUE 1 e-01 by using a MAC control element (MAC CE) (operation 1 e-65).

FIG. 1F illustrates a diagram for describing a procedure in which a UEsupporting an idle mode measurement releases an RRC connection with aneNB/gNB to perform the idle mode measurement and the eNB/gNB configuresCA for the UE, based on a result of the idle mode measurement, accordingto an embodiment of the disclosure.

According to an embodiment of the disclosure, the UE may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in the RRC idle mode. The UE may measure one or more frequencies inthe RRC idle mode and may store results of the measurements, separately.In other words, the eNB/gNB may transmit measurement configurationinformation available in the RRC idle mode (measIdleConfig) in anRRCConnectionRelease message or system information (e.g., SIB5 or a newSIBx) to the UE, and the UE may measure at least one frequency, based onthe measIdleConfig, and, when a set condition is satisfied, may transitto the RRC connected mode and then transmit a MeasurementReport messageto the eNB/gNB. Alternatively, when the eNB/gNB transmits aUEInformationRequest message to the UE that has transited from the RRCidle mode to the RRC connected mode in order to request a measurementresult, the UE in the RRC connected mode may transmit to the eNB/gNB aUEInformationResponse message including a result of a measurementperformed in the RRC idle mode. This may delay application of existingCA by a long time.

Referring to FIG. 1F, a UE 1 f-01 may establish an RRC connection withan eNB/gNB 1 f-02 and thus may be in the RRC connected mode (operation 1f-03). When the UE 1 f-01 that transmits or receives data in the RRCconnected mode does not transmit or receive data for a certain reason orfor a certain time, the eNB/gNB 1 f-02 may transmit anRRCConnectionRelease message to the UE 1 f-01 such that the UE 1 f-01switches to the RRC idle mode (operation 1 f-05). TheRRCConnectionRelease message may include measurement configurationinformation available in the RRC idle mode (measIdleConfig). ThemeasIdleConfig being an IE may include at least one of the followingparameters.

-   -   A carrier frequency list used for measurement by a UE in the RRC        idle mode (measIdleCarrierList)

According to an embodiment, each carrier frequency that is used formeasurement in the RRC idle mode may include at least one of aCarrierFreq containing an absolute radio frequency channel number value(ARFCN-Value), an indicator (allowedMeasBandwidth) indicating ameasurement-allowable bandwidth, a cell list (validityArea) on which aUE is requested to perform an idle mode measurement, a cell list(measCellList) on which the UE is requested to perform an idle modemeasurement and report a result of the idle mode measurement, athreshold of reference signal received power (RSRP) and/or referencesignal received quality (RSRQ) used by the UE to determine whether toreport cells measured through an idle mode measurement, or an indicator(reportQuantities) indicating whether the UE reports a result value ofthe cells measured through an idle mode measurement with the RSRP, orthe RSRQ, or both the RSRP or the RSRQ.

The carrier frequency list (measIdleCarrierList) used for measurement inthe RRC idle mode may be included in singular or in plural. For example,the measIdleCarrierList may be divided into measIdleCarrierListEUTRA andmeasIdleCarrierListNR according to radio access technologies.

-   -   A value representing a duration while the UE performs        measurement in the RRC idle mode (measIdleDuration)

According to an embodiment, the measIdleDuration may represent a timerT311 value or a new timer T3xx value.

The UE may perform idle mode measurement after the UE receives theRRCConnectionRelease message and before the measIdleDuration expires.

When the RRCConnectionRelease message includes measIdleConfig inoperation 1 f-05, the UE 1 f-01 may delete VarMeasIdleConfig andVarMeasIdleReport being UE variables. The UE may store, in themeasIdleConfig, the value representing the duration while the UEperforms measurement in the RRC idle mode (e.g., measIdleDuration), andmay drive a timer by applying the value representing the duration whilethe UE performs measurement in the RRC idle mode. When theRRCConnectionRelease message includes the carrier frequency list usedfor measurement by the UE in the RRC idle mode, the UE 1 f-01 may storethe carrier frequency list and perform idle mode measurement while atimer is operating in supportable carriers, based on the stored carrierfrequency list (operation 1 f-11). When the RRCConnectionRelease messagedoes not include the carrier frequency list used for measurement by theUE in the RRC idle mode, the UE 1 f-01 may receive system information bysearching for and camping on a suitable cell, via a cell selectionprocedure and/or a cell reselection procedure (operation 1 f-10). When acarrier frequency list measIdleConfigSIB used for measurement in the RRCidle mode is included in the received system information, the UE 1 f-01may store the received measIdleConfigSIB while the on-going operation ofthe timer continues, or may replace the carrier frequency list withinthe UE 1 f-01, based on the received measIdleConfigSIB, and perform idlemode measurement while the timer is operating in supportable carriers,based on the carrier frequency list (operation 1 f-11). When systeminformation that is broadcast by a target cell does not include themeasIdleConfigSIB through a cell reselection procedure, the UE 1 f-01may stop the on-going idle mode measurement.

The UE 1 f-01 may trigger a random access in order to establish an RRCconnection with the eNB/gNB 1 f-02 (operation 1 f-13). When the randomaccess is triggered, the UE 1 f-01 may select a PRACH occasion andtransmit a Random Access Preamble to the eNB/gNB 1 f-02 (operation 1f-15). In response to the Random Access Preamble, the eNB/gNB 1 f-02 maytransmit an RAR message to the UE 1 f-01 (operation 1 f-20). The UE 1f-01 in the RRC idle mode may establish an inverse directiontransmission synchronization with the eNB/gNB 1 f-02 through operations1 f-15 and 1 f-20.

The UE 1 f-01 in the RRC idle mode that has established an inversedirection transmission synchronization may perform an RRC connectionestablishment procedure with the eNB/gNB 1 f-02. First, the UE 1 f-01may transmit a RRCConnectionRequest message to the eNB/gNB 1 f-02(operation 1 f-20). The RRCConnectionRequest message may include anidentity of the UE 1 f-01, an establishment cause for establishing anRCC connection, or the like. In response to the RRCConnectionRequestmessage, the eNB/gNB 1 f-02 may transmit an RRCConnectionSetup messageto the UE 1 f-01 (operation 1 f-30). The RRCConnectionSetup message mayinclude radio resource setup information (RadioResourceConfigDedicated,radioBearerConfig, or masterCellGroup). In response to theRRCConnectionSetup message, the UE 1 f-01 may set the radio resourcesetup information and may switch the RRC idle mode to the RRC connectedmode (operation 1 f-31). RRC connection establishment may be accompaniedby connection of SRB1. Accordingly, an RRC message or an RRC messageincluding a NAS message or an initial NAS message that is a controlmessage between a UE and a BS may be transmitted and received via SRB1.When the system information received in operation 1 f-10 includes anindicator (idleModeMeasurements) indicating that the eNB/gNB 1 f-02 isable to process idle mode measurement of the UE 1 f-01, and theVarMeasIdleReport as a UE variable includes idle mode measurementinformation by performing idle mode measurement in operation 1 f-11, theUE 1 f-01 switched to the RRC connected mode may include, in anRRCConnectionSetupComplete message, an indicator (idleMeasAvailable)indicating that an idle mode measurement report is possible. The UE 1f-01 may stop when the timer (for example, T311 or T3xx) keepsoperating. The UE 1 f-01 in the RRC connected mode may transmit theRRCConnectionSetupComplete message to the eNB/gNB 1 f-02 through SRB1(operation 1 f-35). The RRCConnectionSetupComplete message may include aservice request message transmitted by the UE 1 f-01 to request an AMFor MME for bearer configuration for a certain service.

When the RRC connection establishment procedure is successfullyperformed, the eNB/gNB 1 f-02 may perform an RRC connectionreconfiguration procedure with the UE 1 f-01. First, the eNB/gNB 1 f-02may transmit an RRCConnectionReconfiguration message to the UE 1 f-01(operation 1 f-40). The RRCConnectionReconfiguration message may includeat least one of configuration information about a DRB to process userdata, configuration information about SRB1 and/or SRB2 via which acontrol message may be transmitted and received, or measurementconfiguration information (measConfig). In response to theRRCConnectionReconfiguration message, the UE 1 f-01 may apply theinformation included in the RRCConnectionReconfiguration message, andthen may transmit an RRCConnectionReconfigurationComplete message to theeNB/gNB 1 f-02 (operation 1 f-45).

When the RRCConnectionSetupComplete message includes the indicator(idleMeasAvailable) indicating that an idle mode measurement report ispossible, in operation 1 f-35, the eNB/gNB 1 f-02 may perform a UEinformation procedure with the UE 1 f-01. The UE information proceduremay be immediately performed without performing the above-described RRCconnection reconfiguration procedure (including operations 1 f-40 and 1f-45). The eNB/gNB 1 f-02 may transmit, to the UE 1 f-01 in the RRCconnected mode, a UEInformationRequest message including an indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC idle mode (operation 1 f-50). When security issuccessfully configured, the UE 1 f-01 that has received theUEInformationRequest message may perform the following processes.

1> When the UEInformationRequest message includes the indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC idle mode and the UE 1 f-01 has stored theVarMeasIdleReport,

2> measResultListIdle included in a UEInformationResponse message is setas a measReportIdle value (or an idleMeasReport value) included in theVarMeasIdleReport.

2> When it is confirmed by lower layers that the UEInformationResponsemessage was transmitted successfully, the VarMeasIdleReport isdiscarded.

1> The UEInformationResponse message is submitted to the lower layersvia the SRB1. The UE 1 f-01 may transmit, to the eNB/gNB 1 f-02, theUEInformationReponse message including a list (measResultListIdle) ofresults of the measurements performed in the RRC idle mode (operation 1f-55).

In the above description, the measResultListIdle as an IE may mean alist of measResultIdle as an IE individually configured for one or moreneighboring inter-frequency carriers by the UE 1 f-01 in the RRC idlemode. A UE according to an embodiment of the disclosure may configuremeasResultIdle for each neighboring inter-frequency carrier whentransmitting the UEInformationResponse message, by using at least one ofthe following methods.

Method 1: The measResultIdle may optionally include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle optionally includes the measurement result        (measResultServingCell) of a serving cell, because there exist        only one serving cell of the UE in the RRC idle mode and        accordingly there is no need to report a plurality of        neighboring inter-frequencies. For example, when        measResultServingCell for each neighboring inter-frequency        carrier is represented in the form of a value of 0 or 1 (or        FALSE or TURE) and is 0 (or FALSE), measResultIdle may not        include measResultServingCell.    -   When the measResultIdle includes measResultServingCell for each        neighboring inter-frequency carrier, the measResultIdle may        include the same serving cell measurement results.    -   The measResultServingCell may include or may not include at        least one of the following result values.    -   RSRP result values (rsrpResult)    -   RSRQ result values (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an absolute radio        frequency channel number value (ARFCN-Value)    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   When there are no measurement results of neighboring cells for        all neighboring inter-frequency carriers, the measResultListIdle        may not be included in the UEInformationResponse message.

Method 2: The measResultIdle may always include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle always includes a serving cell measure result        for each neighboring inter-frequency carrier, and the serving        cell measurement results are the same as each other. When there        is no measurement result of neighboring cells for each        neighboring inter-frequency carrier, the measResultListIdle does        not include the neighboring inter-frequency carrier. When there        are no measurement results of neighboring cells for all        neighboring inter-frequency carriers, the measResultListIdle may        not be included in the UEInformationResponse message.    -   The measResultServingCell may include at least one of the        following result values.    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an absolute radio        frequency channel number value (ARFCN-Value)    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)

When the measResultListIdle is included in the UEInformationResponsemessage in operation 1 f-55, the eNB/gNB 1 f-02 may perform an RRCconnection reconfiguration procedure with the UE 1 f-01. First, theeNB/gNB 1 f-02 may transmit an RRCConnectionReconfiguration message tothe UE 1 f-01 (operation 1 f-60). The RRCConnectionReconfigurationmessage may include at least one of configuration information about aDRB to process user data, configuration information about SRB1 and/orSRB2 via which a control message may be transmitted and received, ormeasurement configuration information (measConfig). In response to theRRCConnectionReconfiguration message, the UE 1 f-01 may apply theinformation included in the RRCConnectionReconfiguration message, andthen may transmit the RRCConnectionReconfigurationComplete message tothe eNB/gNB 1 f-02 (operation 1 f-65).

The RRCConnectionReconfiguration message in operation 1 f-60 may includea common configuration parameter for configuration of several SCells(Scell Group configuration) at one time or a configuration parameter(SCell configuration) for each of the SCells. When theRRCConnectionReconfiguration message includes a common configurationparameter for several SCells, at least one of the following methods maybe applied.

Method 1: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

Method 2: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group and different parameters for differentSCells in each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include an        indicator for indicating delta configuration to apply different        parameters for different SCells in each SCell group. When the        indicator is included in a specific Scell, a common parameter of        an Scell group to which SCells belong. When the indicator is not        included in the specific Scell, only parameters different from        the common parameter of the Scell group may be additionally        included or only the parameter of the specific Scell may be        included.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

The eNB/gNB 1 f-02 may apply CA by indicating a state (activated,dormant, or deactivated state) of each SCell configured in the UE 1 f-01by using a MAC CE (operation 1 f-70).

FIG. 1G illustrates a diagram for describing a procedure in which a UEsupporting an idle mode measurement releases an RRC connection with aneNB/gNB to perform the idle mode measurement and the eNB/gNB configuresCA for the UE, based on a result of the idle mode measurement, accordingto an embodiment of the disclosure.

The UE according to an embodiment of the disclosure may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in an RRC inactive mode. The UE may separately measure one or morefrequencies in the RRC inactive mode and may store results of themeasurements. In other words, the eNB/gNB may signal measurementconfiguration information available in the RRC inactive mode(measIdleConfig) in an RRCConnectionRelease message or systeminformation (e.g., SIB5 or a new SIBx) to the UE, and the UE may measureat least one frequency, based on the measIdleConfig, and, when a setcondition is satisfied, may transit to the RRC connected mode and thentransmit a MeasurementReport message to the eNB/gNB. Alternatively, whenthe eNB/gNB transmits a UEInformationRequest message to the UE that hastransited from the RRC inactive mode to the RRC connected mode in orderto request a measurement result, the UE in the RRC connected mode maytransmit to the eNB/gNB a UEInformationResponse message including aresult of a measurement performed in the RRC inactive mode. This maydelay application of existing CA by a long time.

Referring to FIG. 1G, a UE 1 g-01 may establish an RRC connection withan eNB/gNB 1 g-02 and thus may be in the RRC connected mode (operation 1g-03). When the UE 1 g-01 that transmits or receives data in the RRCconnected mode does not transmit or receive data for a certain reason orfor a certain time, the eNB/gNB 1 g-02 may transmit anRRCConnectionRelease message to the UE 1 f-01 such that the UE 1 g-01switches to the RRC inactive mode (operation 1 g-05). TheRRCConnectionRelease message may include measurement configurationinformation available in the RRC inactive mode (measIdleConfig). ThemeasIdleConfig being an IE may include at least one of the followingparameters.

-   -   A carrier frequency list used for measurement by a UE in the RRC        inactive mode (measIdleCarrierList)

According to an embodiment, each carrier frequency that is used formeasurement in the RRC inactive mode may include at least one of aCarrierFreq containing an absolute radio frequency channel number value(ARFCN-Value), an indicator (allowedMeasBandwidth) indicating ameasurement-allowable bandwidth, a cell list (validityArea) on which aUE is requested to perform an idle mode measurement, a cell list(measCellList) on which the UE is requested to perform an idle modemeasurement and report a result of the idle mode measurement, athreshold of reference signal received power (RSRP) and/or referencesignal received quality (RSRQ) used by the UE to determine whether toreport cells measured through an idle mode measurement, or an indicator(reportQuantities) indicating whether the UE reports a result value ofthe cells measured through an idle mode measurement with the RSRP, orthe RSRQ, or both the RSRP and the RSRQ.

The carrier frequency list used for measurement in the RRC inactive modemay be included in singular or in plural. For example, the carrierfrequency list may be represented by measIdleCarrierListEUTRA ormeasIdleCarrierListNR according to radio access technologies.

-   -   A value representing a duration while the UE performs        measurement in the RRC inactive mode (measIdleDuration)

According to an embodiment, the measIdleDuration may represent a timerT311 value or a new timer T3xx value.

The UE may perform idle mode measurement after the UE receives theRRCConnectionRelease message and before the measIdleDuration expires.

When the RRCConnectionRelease message includes measIdleConfig inoperation 1 g-05, the UE 1 g-01 may delete VarMeasIdleConfig andVarMeasIdleReport being UE variables. The UE may store, in themeasIdleConfig, the value representing the duration while the UEperforms measurement in the RRC inactive mode (e.g., measIdleDuration),and may drive a timer by applying the value representing the durationwhile the UE performs measurement in the RRC inactive mode. When theRRCConnectionRelease message includes the carrier frequency list usedfor measurement by the UE in the RRC inactive mode, the UE 1 g-01 maystore the carrier frequency list and perform idle mode measurement whilea timer is operating in supportable carriers, based on the storedcarrier frequency list (operation 1 g-11). When the RRCConnectionReleasemessage does not include the carrier frequency list used for measurementby the UE in the RRC inactive mode, the UE 1 g-01 may receive systeminformation by searching for and camping on a suitable cell, via a cellselection procedure and/or a cell reselection procedure (operation 1g-10). When a carrier frequency list measIdleConfigSIB used formeasurement in the RRC inactive mode is included in the received systeminformation, the UE 1 g-01 may store the received measIdleConfigSIBwhile the on-going operation of the timer continues, or may replace thecarrier frequency list within the UE 1 g-01, based on the receivedmeasIdleConfigSIB, and perform idle mode measurement while the timer isoperating in supportable carriers, based on the carrier frequency list(operation 1 g-11). When system information that is broadcast by atarget cell does not include the measIdleConfigSIB through a cellreselection procedure, the UE 1 g-01 may stop the on-going idle modemeasurement.

The UE 1 g-01 may trigger a random access in order to establish an RRCconnection with the eNB/gNB 1 g-02 (operation 1 g-13). When the randomaccess is triggered, the UE 1 g-01 may select a PRACH occasion andtransmit a Random Access Preamble to the eNB/gNB 1 g-02 (operation 1g-15). In response to the Random Access Preamble, the eNB/gNB 1 g-02 maytransmit an RAR message to the UE 1 g-01 (operation 1 g-20). The UE 1g-01 in the RRC inactive mode may establish an inverse directiontransmission synchronization with the eNB/gNB 1 g-02 through operations1 g-15 and 1 g-20.

The UE 1 g-01 in the RRC inactive mode that has established an inversedirection transmission synchronization may perform an RRC connectionresume procedure with the eNB/gNB 1 g-02. First, the UE 1 g-01 maytransmit a RRCConnectionResumeRequest message to the eNB/gNB 1 g-02(operation 1 g-20). The RRCConnectionResumeRequest message may includean identity of the UE 1 g-01 (resumeIdentity), a cause for resuming anRCC connection (resumeCause), or the like. In response to theRRCConnectionResumeRequest message, the eNB/gNB 1 g-02 may transmit, tothe UE 1 g-01, an RRCConnectionResume message, an RRCConnectionReleasemessage, an RRCConnectionReject message, or an RRCConnectionSetupmessage (operation 1 g-30).

The RRCConnectionResumeRequest message may include radio resource setupinformation (RadioResourceConfigDedicated and/or radioBearerConfigand/or masterCellGroup and/or secondaryCellGroup). Alternatively, theRRCConnectionResumeRequest message may include measurement configurationinformation (measIdleConfig). The measurement configuration informationmay be signaled separately for a master cell group (MCG) and a secondarycell group (SCG). In response to the RRCConnectionResume message, the UE1 g-01 may set the radio resource setup information and may switch theRRC inactive to the RRC connected mode (operation 1 g-31). When thesystem information received in operation 1 g-10 includes an indicator(idleModeMeasurements) indicating that the eNB/gNB 1 g-02 is able toprocess idle mode measurement of the UE 1 g-01, and theVarMeasIdleReport as a UE variable includes idle mode measurementinformation by performing idle mode measurement in operation 1 g-11, theUE 1 g-01 switched to the RRC connected mode may include, in anRRCConnectionResumeComplete message, an indicator (idleMeasAvailable)indicating that an idle mode measurement report is possible. The UE 1g-01 may stop when the timer (for example, T311 or T3xx) keepsoperating. The UE 1 g-01 in the RRC connected mode may transmit theRRCConnectionResumeComplete message to the eNB/gNB 1 g-02 through SRB1(operation 1 g-35).

When the eNB/gNB 1 g-02 transmits the RRCConnectionRelease message tothe UE 1 g-01 in operation 1 g-30, the UE 1 g-01 may apply at least oneof the following methods.

-   -   When the RRCConnectionRelease message does not include the        measIdleConfig,

the UE 1 g-01 may keep driving the timer driven in operation 1 g-05 orstop the timer, or may initialize the timer value of the timer to apre-stored timer value and then drive the timer. When the UE 1 g-01stops the timer, the UE 1 g-01 may delete the VarMeasIdleConfig and theVarMeasIdleReport as UE variables and may stop the idle modemeasurement. When the UE 1 g-01 keeps driving the timer, the UE 1 g-01may maintain pre-stored UE variable values and may continuously performthe idle mode measurement until the timer expires. When the UE 1 g-01initializes the timer value of the timer to a pre-stored timer value andthen drive the timer, the UE 1 g-01 may maintain pre-stored UE variablevalues and may perform the idle mode measurement until a newly driventimer expires.

-   -   When the RRCConnectionRelease message includes the        measIdleConfig,

the UE 1 g-01 may replace a value stored in operation 1 g-05 or 1 g-10.

The UE 1 g-01 may continue to drive the timer driven in operation 1 g-05or re-drive the timer with a measuring-performing value newly signaledin operation 1 g-30, thereby performing the idle mode measurement untilthe re-driven timer expires.

-   -   When the RRCConnectionRelease message includes suspendConfig,

the UE 1 g-01 may maintain the RRC inactive mode and re-perform the RRCconnection resume procedure with the eNB/gNB 1 g-02.

-   -   When the RRCConnectionRelease message does not include        suspendConfig,

the UE 1 g-01 may transit to the RRC idle mode and perform an RRCconnection establishment procedure with the eNB/gNB 1 g-02 according tothe above-describe embodiment.

When the eNB/gNB 1 g-02 transmits the RRCConnectionReject message to theUE 1 g-01 in operation 1 g-30, the UE 1 g-01 may apply at least one ofthe following methods.

-   -   When the RRCConnectionReject message includes waitTime,

the UE 1 g-01 may keep driving the timer driven in operation 1 g-05 ormay initialize the timer value of the timer to a pre-stored timer valueand then drive the timer. When the UE 1 g-01 stops the timer, the UE 1g-01 may delete the VarMeasIdleConfig and the VarMeasIdleReport as UEvariables and may stop the idle mode measurement. When the UE 1 g-01keeps driving the timer, the UE 1 g-01 may maintain pre-stored UEvariable values and may continuously perform the idle mode measurementuntil the timer expires. When the UE 1 g-01 initializes the timer valueof the timer to a pre-stored timer value and then drive the timer, theUE 1 g-01 may maintain pre-stored UE variable values and may perform theidle mode measurement until a newly driven timer expires. After the UE 1g-01 transits to the RRC idle mode, receives the RRCConnectionRejectmessage, and then waits for the waitTime, the UE 1 g-01 may perform anRRC connection establishment procedure with the eNB/gNB 1 g-02 accordingto the above-describe embodiment. Alternatively, after the UE 1 g-01maintains the RRC inactive mode, receives the RRCConnectionRejectmessage, and then waits for the waitTime, the UE 1 g-01 may re-performan RRC connection resume procedure with the eNB/gNB 1 g-02 according tothe above-describe embodiment.

-   -   When the RRCConnectionReject message does not include the        waitTime,

the UE 1 g-01 may keep driving the timer driven in operation 1 g-05 ormay initialize the timer value of the timer to a pre-stored timer valueand then drive the timer. When the UE 1 g-01 stops the timer, the UE 1g-01 may delete the VarMeasIdleConfig and the VarMeasIdleReport as UEvariables and may stop the idle mode measurement. When the UE 1 g-01keeps driving the timer, the UE 1 g-01 may maintain pre-stored UEvariable values and may continuously perform the idle mode measurementuntil the timer expires. When the UE 1 g-01 initializes the timer valueof the timer to a pre-stored timer value and then drive the timer, theUE 1 g-01 may maintain pre-stored UE variable values and may perform theidle mode measurement until a newly driven timer expires. After the UE 1g-01 transits to the RRC idle mode, receives the RRCConnectionRejectmessage, and then waits for the waitTime, the UE 1 g-01 may perform anRRC connection establishment procedure with the eNB/gNB 1 g-02 accordingto the above-describe embodiment.

When the eNB/gNB 1 g-02 transmits an RRCConnectionResume message or anRRCConnection establishment message to the UE 1 g-01 in operation 1g-30, the UE 1 g-01 may stop the timer driven in operation 1 g-05 andmay delete the VarMeasIdleConfig and the VarMeasIdleReport as UEvariables and stop the idle mode measurement.

When the RRC connection establishment procedure or the RRC connectionresume procedure is successfully performed, the eNB/gNB 1 g-02 mayperform an RRC connection reconfiguration procedure with the UE 1 g-01.First, the eNB/gNB 1 g-02 may transmit an RRCConnectionReconfigurationmessage to the UE 1 g-01 (operation 1 g-40). TheRRCConnectionReconfiguration message may include at least one ofconfiguration information about a DRB to process user data,configuration information about SRB1 and/or SRB2 via which a controlmessage may be transmitted and received, or measurement configurationinformation (measConfig). In response to theRRCConnectionReconfiguration message, the UE 1 g-01 may apply theinformation included in the RRCConnectionReconfiguration message, andthen may transmit an RRCConnectionReconfigurationComplete message to theeNB/gNB 1 g-02 (operation 1 g-45).

When the RRCConnectionSetupComplete message or theRRCConnectionResumeComplete message includes the indicator(idleMeasAvailable) indicating that an idle mode measurement report ispossible, in operation 1 g-35, the eNB/gNB 1 g-02 may perform a UEinformation procedure with the UE 1 g-01. The UE information proceduremay be immediately performed without performing the above-described RRCconnection reconfiguration procedure (including operations 1 g-40 and 1g-45). The eNB/gNB 1 g-02 may transmit, to the UE 1 g-01 in the RRCconnected mode, a UEInformationRequest message including an indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC idle mode or the RRC inactive mode (operation 1g-50). When security is successfully configured, the UE 1 g-01 that hasreceived the UEInformationRequest message may perform the followingprocesses.

1> When the UEInformationRequest message includes the indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC inactive mode or the RRC idle mode and the UE 1g-01 has stored the VarMeasIdleReport,

2> measResultListIdle included in a UEInformationResponse message is setas a measReportIdle value (or an idleMeasReport value) included in theVarMeasIdleReport.

2> When it is confirmed by lower layers that the UEInformationResponsemessage was transmitted successfully, the VarMeasIdleReport isdiscarded.

1> The UEInformationResponse message is submitted to the lower layersvia the SRB1. The UE 1 g-01 may transmit, to the eNB/gNB 1 g-02, theUEInformationReponse message including a list (measResultListIdle) ofresults of the measurements performed in the RRC inactive mode or theRRC idle mode (operation 1 g-55).

In the above description, the measResultListIdle as an IE may mean alist of measResultIdle as an IE individually configured for one or moreneighboring inter-frequency carriers by the UE 1 g-01 in the RRCinactive mode or the RRC idle mode. A UE according to an embodiment ofthe disclosure may configure measResultIdle for each neighboringinter-frequency carrier when transmitting the UEInformationResponsemessage, by using at least one of the following methods.

Method 1: The measResultIdle may optionally include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle optionally includes the measurement result        (measResultServingCell) of a serving cell, because there exist        only one serving cell of the UE in the RRC inactive mode or the        RRC idle mode and accordingly there is no need to report a        plurality of neighboring inter-frequencies. For example, when        measResultServingCell for each neighboring inter-frequency        carrier is represented in the form of a value of 0 or 1 (or        FALSE or TURE) and is 0 (or FALSE), the measResultIdle may not        include measResultServingCell.    -   When the measResultIdle includes the measResultServingCell, the        measResultIdle may include the same serving cell measurement        results for each neighboring inter-frequency carrier.    -   The measResultServingCell may include or may not include at        least one of the following result values.    -   RSRP result values (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an absolute radio        frequency channel number value (ARFCN-Value)    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   When there are no measurement results of neighboring cells for        all neighboring inter-frequency carriers, the measResultListIdle        may not be included in the UEInformationResponse message.

Method 2: The measResultIdle may always include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle always includes a serving cell measure result        for each neighboring inter-frequency carrier, and the serving        cell measurement results are the same as each other. When there        is no measurement result of neighboring cells for each        neighboring inter-frequency carrier, the measResultListIdle does        not include the neighboring inter-frequency carrier. When there        are no measurement results of neighboring cells for all        neighboring inter-frequency carriers, the measResultListIdle may        not be included in the UEInformationResponse message.    -   The measResultServingCell may include at least one of the        following result values.    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an absolute radio        frequency channel number value (ARFCN-Value)    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)

When the measResultListIdle is included in the UEInformationResponsemessage in operation 1 g-55, the eNB/gNB 1 g-02 may perform an RRCconnection reconfiguration procedure with the UE 1 g-01. First, theeNB/gNB 1 g-02 may transmit an RRCConnectionReconfiguration message tothe UE 1 g-01 (operation 1 g-60). The RRCConnectionReconfigurationmessage may include at least one of configuration information about aDRB to process user data, configuration information about SRB1 and/orSRB2 via which a control message may be transmitted and received, ormeasurement configuration information (measConfig). In response to theRRCConnectionReconfiguration message, the UE 1 g-01 may apply theinformation included in the RRCConnectionReconfiguration message, andthen may transmit the RRCConnectionReconfigurationComplete message tothe eNB/gNB 1 g-02 (operation 1 g-65).

The RRCConnectionReconfiguration message in operation 1 g-60 may includea common configuration parameter for configuration of several SCells(Scell Group configuration) at one time or a configuration parameter(SCell configuration) for each of the SCells. When theRRCConnectionReconfiguration message includes a common configurationparameter for several SCells, at least one of the following methods maybe applied.

Method 1: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

Method 2: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group and different parameters for differentSCells in each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include an        indicator for indicating delta configuration to apply different        parameters for different SCells in each SCell group. When the        indicator is included in a specific Scell, a common parameter of        an Scell group to which SCells belong. When the indicator is not        included in the specific Scell, only parameters different from        the common parameter of the Scell group may be additionally        included or only the parameter of the specific Scell may be        included.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

The eNB/gNB 1 g-02 may apply CA by indicating a state (activated,dormant, or deactivated state) of each SCell configured in the UE 1 g-01by using a MAC CE (operation 1 g-70).

FIG. 1H illustrates a diagram for describing a procedure in which a UEsupporting an idle mode measurement releases an RRC connection with aneNB/gNB to perform the idle mode measurement and the eNB/gNB configuresCA for the UE, based on a result of the idle mode measurement, accordingto an embodiment of the disclosure.

According to an embodiment of the disclosure, the UE may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in the RRC idle mode or the RRC inactive mode. The UE mayseparately measure one or more frequencies in the RRC idle mode or theRRC inactive mode and may store results of the measurements. In otherwords, the eNB/gNB may signal measurement configuration informationavailable in the RRC idle mode or the RRC inactive mode (measIdleConfig)in an RRCConnectionRelease message or system information (e.g., SIB5 ora new SIBx) to the UE, and the UE may measure at least one frequency,based on the measIdleConfig, and, when a set condition is satisfied, maytransit to the RRC connected mode and then transmit a MeasurementReportmessage to the eNB/gNB. Alternatively, when the eNB/gNB transmits aUEInformationRequest message to the UE that has transited from the RRCidle mode or the RRC inactive mode to the RRC connected mode in order torequest a measurement result, the UE in the RRC connected mode maytransmit to the eNB/gNB a UEInformationResponse message including aresult of a measurement performed in the RRC idle mode or the RRCinactive mode. Alternatively, the UE in the RRC connected mode maytransmit to the eNB/gNB an UEAssistanceInformation message including aresult of the measurement performed in the RRC idle mode or the RRCinactive mode. This may delay application of existing CA by a long time.

Referring to FIG. 1H, a UE 1 h-01 may establish an RRC connection withan eNB/gNB 1 h-02 and thus may be in the RRC connected mode (operation 1h-03). When the UE 1 h-01 that transmits or receives data in the RRCconnected mode does not transmit or receive data for a certain reason orfor a certain time, the eNB/gNB 1 h-02 may transmit anRRCConnectionRelease message to the UE 1 h-01 such that the UE 1 h-01switches to the RRC inactive mode or the RRC idle mode (operation 1h-05). The RRCConnectionRelease message may include measurementconfiguration information available in the RRC inactive mode or the RRCidle mode (measIdleConfig). The measIdleConfig being an IE may includeat least one of the following parameters.

-   -   A carrier frequency list used for measurement by a UE in the RRC        inactive mode or the RRC idle mode (measIdleCarrierList)

According to an embodiment, each carrier frequency that is used formeasurement in the RRC inactive mode or the RRC idle mode may include atleast one of a CarrierFreq containing an absolute radio frequencychannel number value (ARFCN-Value), an indicator (allowedMeasBandwidth)indicating a measurement-allowable bandwidth, a cell list (validityArea)on which a UE is requested to perform an idle mode measurement, a celllist (measCellList) on which the UE is requested to perform an idle modemeasurement and report a result of the idle mode measurement, athreshold of reference signal received power (RSRP) and/or referencesignal received quality (RSRQ) used by the UE to determine whether toreport cells measured through an idle mode measurement, or an indicator(reportQuantities) indicating whether the UE reports a result value ofthe cells measured through an idle mode measurement with the RSRP, theRSRQ, or both the RSRP and the RSRQ.

The carrier frequency list used for measurement in the RRC inactive modeor the RRC idle mode may be included in singular or in plural. Forexample, the measIdleCarrierList may be divided intomeasIdleCarrierListEUTRA and measIdleCarrierListNR according to radioaccess technologies.

-   -   A value representing a duration while the UE performs        measurement in the RRC inactive mode or the RRC idle mode        (measIdleDuration)

According to an embodiment, the measIdleDuration may represent a timerT311 value or a new timer T3xx value.

The UE may perform idle mode measurement after the UE receives theRRCConnectionRelease message and before the measIdleDuration expires.

When the RRCConnectionRelease message includes measIdleConfig inoperation 1 h-05, the UE 1 h-01 may delete VarMeasIdleConfig andVarMeasIdleReport being UE variables. The UE may store, in themeasIdleConfig, the value representing the duration while the UEperforms measurement in the RRC inactive mode or the RRC idle mode(e.g., measIdleDuration), and may drive a timer by applying the valuerepresenting the duration while the UE performs measurement in the RRCinactive mode or the RRC idle mode. When the RRCConnectionReleasemessage includes the carrier frequency list used for measurement by theUE in the RRC inactive mode or the RRC idle mode, the UE 1 h-01 maystore the carrier frequency list and perform idle mode measurement whilea timer is operating in supportable carriers, based on the storedcarrier frequency list (operation 1 h-11). When the RRCConnectionReleasemessage does not include the carrier frequency list used for measurementby the UE in the RRC inactive mode or the RRC idle mode, the UE 1 h-01may receive system information by searching for and camping on asuitable cell, via a cell selection procedure and/or a cell reselectionprocedure (operation 1 h-10). When a carrier frequency listmeasIdleConfigSIB used for measurement in the RRC inactive mode or theRRC idle mode is included in the received system information, the UE 1h-01 may store the received measIdleConfigSIB while the on-goingoperation of the timer continues, or may replace the carrier frequencylist within the UE 1 h-01, based on the received measIdleConfigSIB, andperform idle mode measurement while the timer is operating insupportable carriers, based on the carrier frequency list (operation 1h-11). When system information that is broadcast by a target cell doesnot include the measIdleConfigSIB through a cell reselection procedure,the UE 1 h-01 may stop the on-going idle mode measurement.

The UE 1 h-01 may trigger a random access in order to establish an RRCconnection with the eNB/gNB 1 h-02 (operation 1 h-13). When the randomaccess is triggered, the UE 1 h-01 may select a PRACH occasion andtransmit a Random Access Preamble to the eNB/gNB 1 h-02 (operation 1h-15). In response to the Random Access Preamble, the eNB/gNB 1 h-02 maytransmit an RAR message to the UE 1 h-01 (operation 1 h-20). The UE 1h-01 in the RRC idle mode or the RRC inactive mode may establish aninverse direction transmission synchronization with the eNB/gNB 1 h-02through operations 1 h-15 and 1 h-20.

The UE 1 h-01 in the RRC inactive mode or the RRC idle mode that hasestablished an inverse direction transmission synchronization mayperform an RRC connection establishment procedure or an RRC connectionresume procedure with the eNB/gNB 1 h-02.

The UE 1 h-01 in the RRC idle mode may transmit anRRCConnectionSetupRequest message to the eNB/gNB 1 h-02 (operation 1h-25). The RRCConnectionRequest message may include an identity of theUE 1 h-01, an establishment cause for establishing an RCC connection, orthe like. In response to the RRCConnectionRequest message, the eNB/gNB 1h-02 may transmit an RRCConnectionSetup message to the UE 1 h-01(operation 1 h-30). The RRCConnectionSetup message may include radioresource setup information (RadioResourceConfigDedicated,radioBearerConfig, masterCellGroup, or secondaryCellGroup).Alternatively, the RRCConnectionSetup message may include measurementconfiguration information (measIdleConfig). The measurementconfiguration information may be signaled separately for a MCG and aSCG. Alternatively, the RRCConnectionSetup message my include a newtimer value to transmit, without a request by the eNB/gNB 1 h-02, aresult of the measurement performed in the RRC idle mode or the RRCinactive mode. For example, a new timer may be driven after receiving anRRCConnectionSetup message, after switching to the RRC connected mode,when transmitting an RRCConnectionSetupComplete message, or after an RRCconnection establishment procedure successfully ends. When the driventimer expires, the UE 1 h-01 may include, in the UEAssistanceInformationmessage, a result of the measurement performed in the RRC inactive modeor the RRC idle mode after the RRC connection establishment proceduresuccessfully ends, and may report the UEAssistanceInformation includingthe result of the measurement in the RRC inactive mode or the RRC idlemode to the eNB/gNB 1 h-02. An event where the UE 1 h-01 in the RRCconnected mode includes, in the UEAssistanceInformation message, aresult of the measurement performed in the RRC inactive mode or the RRCidle mode through the RRCConnectionSetup message or via a terminaloperation after the RRC connection establishment procedure successfullyends, and reports the UEAssistanceInformation message including theresult of the measurement in the RRC inactive mode or the RRC idle modeto the eNB/gNB 1 h-02 may be defined. For example, when theRRCConnectionSetup message does not include Scell group configurationinformation, or when the UE 1 h-01 includes, in theRRCConnectionSetupComplete message, an indicator (idleMeasAvailable)indicating that an idle mode measurement report is possible andtransmits the RRCConnectionSetupComplete message including the indicator(idleMeasAvailable) to the eNB/gNB 1 h-02, or when the eNB/gNB 1 h-02does not configure a SCell Group for a certain time period after the UE1 h-01 transmits the RRCConnectionSetupComplete message including theindicator (idleMeasAvailable) to the eNB/gNB 1 h-02, or when the UE 1h-01 transmits, to the eNB/gNB 1 h-02, the RRCConnectionSetupCompletemessage not including the indicator (idleMeasAvailable) indicating thatan idle mode measurement report is possible, even when the modemeasurement report is possible, or when the UE 1 h-01 switched to theRRC connected mode determines to transmit or receive a plurality ofpieces of data, or when the UE 1 h-01 desires to quickly apply CA, orwhen the eNB/gNB 1 h-02 does not particularly request a measurementresult until the above-described timer expires, the UE 1 h-01 in the RRCconnected mode may include, in the UEAssistanceInformation message, aresult of the measurement performed in the RRC inactive mode or the RRCidle mode and report the UEAssistanceInformation message including theresult of the measurement in the RRC inactive mode or the RRC idle modeto the eNB/gNB 1 h-02. In response to the RRCConnectionSetup message,the UE 1 h-01 may set the radio resource setup information and mayswitch the RRC idle mode to the RRC connected mode (operation 1 h-31).When the system information received in operation 1 h-10 includes anindicator (idleModeMeasurements) indicating that the eNB/gNB 1 h-02 isable to process idle mode measurement of the UE 1 h-01, and theVarMeasIdleReport as a UE variable includes idle mode measurementinformation by performing idle mode measurement in operation 1 h-11, theUE 1 h-01 switched to the RRC connected mode may include, in anRRCConnectionSetupComplete message, an indicator (idleMeasAvailable)indicating that an idle mode measurement report is possible. The UE 1h-01 may stop when the timer (for example, T311 or T3xx) keepsoperating. The UE 1 h-01 in the RRC connected mode may transmit theRRCConnectionSetupComplete message to the eNB/gNB 1 h-02 through SRB1(operation 1 h-35). The RRCConnectionSetupComplete message may include aservice request message transmitted by the UE 1 h-01 to request an AMFor MME for bearer configuration for a certain service.

When the RRC connection establishment procedure is successfullyperformed, the eNB/gNB 1 h-02 may perform an RRC connectionreconfiguration procedure with the UE 1 h-01. First, the eNB/gNB 1 h-02may transmit an RRCConnectionReconfiguration message to the UE 1 h-01(operation 1 h-40). The RRCConnectionReconfiguration message may includeat least one of configuration information about a DRB to process userdata, configuration information about SRB1 and/or SRB2 via which acontrol message may be transmitted and received, or measurementconfiguration information (measConfig). Alternatively, theRRCConnectionReconfiguration message my include a new timer value totransmit, without a request by the eNB/gNB 1 h-02, a result of themeasurement performed in the RRC idle mode or the RRC inactive mode. Forexample, a new timer may be driven when receiving anRRCConnectionReconfiguration message, when transmitting anRRCConnectionReconfigurationComplete message, or after an RRC connectionreconfiguration procedure successfully ends. When the timer expires, theUE 1 h-01 in the RRC connected mode may include, in theUEAssistanceInformation message, a result of the measurement performedin the RRC inactive mode or the RRC idle mode after the RRC connectionreconfiguration procedure successfully ends, and may report theUEAssistanceInformation message including the result of the measurementin the RRC inactive mode or the RRC idle mode to the eNB/gNB 1 h-02. Anevent where the UE 1 h-01 in the RRC connected mode includes, in theUEAssistanceInformation message, a result of the measurement performedin the RRC inactive mode or the RRC idle mode through theRRCConnectionReconfiguration message or via a terminal operation andreports the UEAssistanceInformation message including the result of themeasurement in the RRC inactive mode or the RRC idle mode to the eNB/gNB1 h-02 may be defined. For example, when theRRCConnectionReconfiguration message does not include Scell groupconfiguration information, or when the UE 1 h-01 includes, in theRRCConnectionSetupComplete message, an indicator (idleMeasAvailable)indicating that an idle mode measurement report is possible andtransmits the RRCConnectionSetupComplete message including the indicator(idleMeasAvailable) to the eNB/gNB 1 h-02, or when the eNB/gNB 1 h-02does not configure a SCell Group for a certain time period after the UE1 h-01 transmits the RRCConnectionReconfigurationComplete messageincluding the indicator (idleMeasAvailable) to the eNB/gNB 1 h-02, orwhen the UE 1 h-01 transmits to the eNB/gNB 1 h-02 theRRCConnectionReconfigurationComplete message not including the indicator(idleMeasAvailable) indicating that an idle mode measurement report ispossible, even when the mode measurement report is possible, or when theUE 1 h-01 in the RRC connected mode determines to transmit or receive aplurality of pieces of data, or when the UE 1 h-01 desires to quicklyapply CA, or when the eNB/gNB 1 h-02 does not particularly request ameasurement result until the above-described timer expires, the UE 1h-01 in the RRC connected mode may include, in theUEAssistanceInformation message, a result of the measurement performedin the RRC inactive mode or the RRC idle mode and may report theUEAssistanceInformation message including the result of the measurementin the RRC inactive mode or the RRC idle mode to the eNB/gNB 1 h-02. Inresponse to the RRCConnectionReconfiguration message, the UE 1 h-01 mayapply the information included in the RRCConnectionReconfigurationmessage, and then may transmit an RRCConnectionReconfigurationCompletemessage to the eNB/gNB 1 h-02 (operation 1 h-45).

After an RRC connection reconfiguration procedure ends, the UE 1 h-01may transmit the UEAssistanceInformation message to the eNB/gNB 1 h-02(operation 1 h-50). As in the above-described method, theUEAssistanceInformation message may be immediately transmitted withoutperforming the above-described RRC connection reconfiguration procedure(including operations 1 h-40 and 1 h-45). The UEAssistanceInformationmessage may include measResultListIdle as a measReportIdle value (or anidleMeasReport value) included in VarMeasIdleReport. ThemeasResultListIdle as an IE may mean a list of measResultIdle as an IEindividually configured for one or more neighboring inter-frequencycarriers by the UE 1 h-01 in the RRC idle mode. A UE according to anembodiment of the disclosure may configure measResultIdle for eachneighboring inter-frequency carrier when transmitting theUEAssistanceInformation message, by using at least one of the followingmethods.

Method 1: The measResultIdle may optionally include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle optionally includes the measurement result        (measResultServingCell) of a serving cell, because there exist        only one serving cell of the UE in the RRC idle mode and        accordingly there is no need to report a plurality of        neighboring inter-frequencies. For example, when        measResultServingCell for each neighboring inter-frequency        carrier is represented in the form of a value of 0 or 1 (or        FALSE or TURE) and is 0 (or FALSE), the measResultIdle may not        include measResultServingCell.    -   When the measResultIdle includes measResultServingCell for each        neighboring inter-frequency carrier, the measResultIdle may        include the same serving cell measurement results.    -   The measResultServingCell may include or may not include at        least one of the following result values.    -   RSRP result values (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   When there are no measurement results of neighboring cells for        all neighboring inter-frequency carriers, the measResultListIdle        may not be included in the UEInformationResponse message.

Method 2: The measResultIdle may always include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle always includes a serving cell measure result        for each neighboring inter-frequency carrier, and the serving        cell measurement results are the same as each other. When there        is no measurement result of neighboring cells for each        neighboring inter-frequency carrier, the measResultListIdle does        not include the neighboring inter-frequency carrier. —When there        are no measurement results of neighboring cells for all        neighboring inter-frequency carriers, the measResultListIdle may        not be included in the UEInformationResponse message.    -   The measResultServingCell may include at least one of the        following result values.    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)

When the measResultListIdle is included in the UEAssistanceInformationmessage in operation 1 h-50, the eNB/gNB 1 h-02 may perform an RRCconnection reconfiguration procedure with the UE 1 h-01. First, theeNB/gNB 1 h-02 may transmit an RRCConnectionReconfiguration message tothe UE 1 h-01 (operation 1 h-60). The RRCConnectionReconfigurationmessage may include at least one of configuration information about aDRB to process user data, configuration information about SRB1 and/orSRB2 via which a control message may be transmitted and received, ormeasurement configuration information (measConfig). In response to theRRCConnectionReconfiguration message, the UE 1 h-01 may apply theinformation included in the RRCConnectionReconfiguration message, andthen may transmit an RRCConnectionReconfigurationComplete message to theeNB/gNB 1 h-02 (operation 1 h-65).

The RRCConnectionReconfiguration message in operation 1 h-60 may includea common configuration parameter for configuration of several SCells(Scell Group configuration) at one time or a configuration parameter(SCell configuration) for each of the SCells. When theRRCConnectionReconfiguration message includes a common configurationparameter for several SCells, at least one of the following methods maybe applied.

Method 1: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

Method 2: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group and different parameters for differentSCells in each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include an        indicator for indicating delta configuration to apply different        parameters for different SCells in each SCell group. When the        indicator is included in a specific Scell, a common parameter of        an Scell group to which SCells belong. When the indicator is not        included in the specific Scell, only parameters different from        the common parameter of the Scell group may be additionally        included or only the parameter of the specific Scell may be        included.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

The eNB/gNB 1 h-02 may apply CA by indicating a state (activated,dormant, or deactivated state) of each SCell configured in the UE 1 h-01by using a MAC CE (operation 1 h-70).

The UE 1 h-01 in the RRC inactive mode may transmit anRRCConnectionResumeRequest message to the eNB/gNB 1 h-02 (operation 1h-25). The RRCConnectionResumeRequest message may include an identity ofthe UE 1 h-01 (resumeIdentity), a cause for resuming an RCC connection(resumeCause), or the like. In response to theRRCConnectionResumeRequest message, the eNB/gNB 1 h-02 may transmit anRRCConnectionResume message to the UE 1 h-01 (operation 1 h-30). TheRRCConnectionResume message may include radio resource setup information(RadioResourceConfigDedicated, radioBearerConfig, masterCellGroup, orsecondaryCellGroup). Alternatively, the RRCConnectionResume message mayinclude measurement configuration information (measIdleConfig). Themeasurement configuration information may be signaled separately for aMCG and a SCG. Alternatively, the RRCConnectionResume message my includea new timer value to transmit, without a request by the eNB/gNB 1 h-02,a result of the measurement performed in the RRC idle mode or the RRCinactive mode. For example, a new timer may be driven after receiving anRRCConnectionResume message, after switching to the RRC connected mode,when transmitting an RRCConnectionResumeComplete message, or after anRRC connection resume procedure successfully ends. When the driven timerexpires, the UE 1 h-01 may include, in the UEAssistanceInformationmessage, a result of the measurement performed in the RRC inactive modeor the RRC idle mode after the RRC connection resume proceduresuccessfully ends, and may report the UEAssistanceInformation includingthe result of the measurement in the RRC inactive mode or the RRC idlemode to the eNB/gNB 1 h-02. An event where the UE 1 h-01 in the RRCconnected mode includes, in the UEAssistanceInformation message, aresult of the measurement performed in the RRC inactive mode or the RRCidle mode through the RRCConnectionResume message or via a terminaloperation after the RRC connection resume procedure successfully ends,and reports the UEAssistanceInformation message including the result ofthe measurement in the RRC inactive mode or the RRC idle mode to theeNB/gNB 1 h-02 may be defined. For example, when the RRCConnectionResumemessage does not include Scell group configuration information, or whenthe UE 1 h-01 includes, in the RRCConnectionResumeComplete message, anindicator (idleMeasAvailable) indicating that an idle mode measurementreport is possible and transmits the RRCConnectionResumeComplete messageincluding the indicator (idleMeasAvailable) to the eNB/gNB 1 h-02, orwhen the eNB/gNB 1 h-02 does not configure a SCell Group for a certaintime period after the UE 1 h-01 transmits theRRCConnectionResumeComplete message including the indicator(idleMeasAvailable) to the eNB/gNB 1 h-02, or when the UE 1 h-01transmits, to the eNB/gNB 1 h-02, the RRCConnectionResumeCompletemessage not including the indicator (idleMeasAvailable) indicating thatan idle mode measurement report is possible, even when the modemeasurement report is possible, or when the UE 1 h-01 switched to theRRC connected mode determines to transmit or receive a plurality ofpieces of data, or when the UE 1 h-01 desires to quickly apply CA, orwhen the eNB/gNB 1 h-02 does not particularly request a measurementresult until the above-described timer expires, the UE 1 h-01 in the RRCconnected mode may include, in the UEAssistanceInformation message, aresult of the measurement performed in the RRC inactive mode or the RRCidle mode and report the UEAssistanceInformation message including theresult of the measurement in the RRC inactive mode or the RRC idle modeto the eNB/gNB 1 h-02. In response to the RRCConnectionResume message,the UE 1 h-01 may set the radio resource setup information and mayswitch the RRC inactive to the RRC connected mode (operation 1 h-31).When the system information received in operation 1 h-10 includes anindicator (idleModeMeasurements) indicating that the eNB/gNB 1 h-02 isable to process idle mode measurement of the UE 1 h-01, and theVarMeasIdleReport as a UE variable includes idle mode measurementinformation by performing idle mode measurement in operation 1 h-11, theUE 1 h-01 switched to the RRC connected mode may include, in anRRCConnectionResumeComplete message, an indicator (idleMeasAvailable)indicating that an idle mode measurement report is possible. The UE 1h-01 may stop when the timer (for example, T311 or T3xx) keepsoperating. The UE 1 h-01 in the RRC connected mode may transmit theRRCConnectionResumeComplete message to the eNB/gNB 1 h-02 through SRB1(operation 1 h-35). The RRCConnectionResumeComplete message may includea service request message transmitted by the UE 1 h-01 to request an AMFor MME for bearer configuration for a certain service.

When the RRC connection resume procedure is successfully performed, theeNB/gNB 1 h-02 may perform an RRC connection reconfiguration procedurewith the UE 1 h-01. First, the eNB/gNB 1 h-02 may transmit anRRCConnectionReconfiguration message to the UE 1 h-01 (operation 1h-40). The RRCConnectionReconfiguration message may include at least oneof configuration information about a DRB to process user data,configuration information about SRB1 and/or SRB2 via which a controlmessage may be transmitted and received, or measurement configurationinformation (measConfig). Alternatively, theRRCConnectionReconfiguration message my include a new timer value totransmit, without a request by the eNB/gNB 1 h-02, a result of themeasurement performed in the RRC idle mode or the RRC inactive mode. Forexample, a new timer may be driven when receiving anRRCConnectionReconfiguration message, when transmitting anRRCConnectionReconfigurationComplete message, or after an RRC connectionreconfiguration procedure successfully ends. When the timer expires, theUE 1 h-01 in the RRC connected mode may include, in theUEAssistanceInformation message, a result of the measurement performedin the RRC inactive mode or the RRC idle mode after the RRC connectionreconfiguration procedure successfully ends, and may report theUEAssistanceInformation message including the result of the measurementin the RRC inactive mode or the RRC idle mode to the eNB/gNB 1 h-02. Anevent where the UE 1 h-01 in the RRC connected mode includes, in theUEAssistanceInformation message, a result of the measurement performedin the RRC inactive mode or the RRC idle mode through theRRCConnectionReconfiguration message or via a terminal operation andreports the UEAssistanceInformation message including the result of themeasurement in the RRC inactive mode or the RRC idle mode to the eNB/gNB1 h-02 may be defined. For example, when theRRCConnectionReconfiguration message does not include Scell groupconfiguration information, or when the UE 1 h-01 includes, in theRRCConnectionResumeComplete message, an indicator (idleMeasAvailable)indicating that an idle mode measurement report is possible andtransmits the RRCConnectionResumeComplete message including theindicator (idleMeasAvailable) to the eNB/gNB 1 h-02, or when the eNB/gNB1 h-02 does not configure a SCell Group for a certain time period afterthe UE 1 h-01 transmits the RRCConnectionReconfigurationComplete messageincluding the indicator (idleMeasAvailable) to the eNB/gNB 1 h-02, orwhen the UE 1 h-01 transmits to the eNB/gNB 1 h-02 theRRCConnectionReconfigurationComplete message not including the indicator(idleMeasAvailable) indicating that an idle mode measurement report ispossible, even when the mode measurement report is possible, or when theUE 1 h-01 in the RRC connected mode determines to transmit or receive aplurality of pieces of data, or when the UE 1 h-01 desires to quicklyapply CA, or when the eNB/gNB 1 h-02 does not particularly request ameasurement result until the above-described timer expires, the UE 1h-01 in the RRC connected mode may include, in theUEAssistanceInformation message, a result of the measurement performedin the RRC inactive mode or the RRC idle mode and may report theUEAssistanceInformation message including the result of the measurementin the RRC inactive mode or the RRC idle mode to the eNB/gNB 1 h-02. Inresponse to the RRCConnectionReconfiguration message, the UE 1 h-01 mayapply the information included in the RRCConnectionReconfigurationmessage, and then may transmit an RRCConnectionReconfigurationCompletemessage to the eNB/gNB 1 h-02 (operation 1 h-45).

After an RRC connection reconfiguration procedure ends, the UE 1 h-01may transmit the UEAssistanceInformation message to the eNB/gNB 1 h-02(operation 1 h-50). As in the above-described method, theUEAssistanceInformation message may be immediately transmitted withoutperforming the above-described RRC connection reconfiguration procedure(including operations 1 h-40 and 1 h-45). The UEAssistanceInformationmessage may include measResultListIdle as a measReportIdle value (or anidleMeasReport value) included in VarMeasIdleReport. ThemeasResultListIdle as an IE means a list of measResultIdle as an IEindividually configured for one or more neighboring inter-frequencycarriers by the UE 1 h-01 in the RRC inactive mode. A UE according to anembodiment of the disclosure may configure measResultIdle for eachneighboring inter-frequency carrier when transmitting theUEAssistanceInformation message), by using at least one of the followingmethods.

Method 1: The measResultIdle may optionally include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle optionally includes the measurement result        (measResultServingCell) of a serving cell, because there exist        only one serving cell of the UE in the RRC inactive mode and        accordingly there is no need to report a plurality of        neighboring inter-frequencies. For example, when        measResultServingCell for each neighboring inter-frequency        carrier is represented in the form of a value of 0 or 1 (or        FALSE or TURE) and is 0 (or FALSE), the measResultIdle may not        include measResultServingCell.    -   When the measResultIdle includes measResultServingCell for each        neighboring inter-frequency carrier, the measResultIdle may        include the same serving cell measurement results.    -   The measResultServingCell may include or may not include at        least one of the following result values.    -   RSRP result values (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   When there are no measurement results of neighboring cells for        all neighboring inter-frequency carriers, the measResultListIdle        may not be included in the UEInformationResponse message.

Method 2: The measResultIdle may always include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle always includes a serving cell measure result        for each neighboring inter-frequency carrier, and the serving        cell measurement results are the same as each other. When there        is no measurement result of neighboring cells for each        neighboring inter-frequency carrier, the measResultListIdle does        not include the neighboring inter-frequency carrier. When there        are no measurement results of neighboring cells for all        neighboring inter-frequency carriers, the measResultListIdle may        not be included in the UEInformationResponse message.    -   The measResultServingCell may include at least one of the        following result values.    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)

When the measResultListIdle is included in the UEAssistanceInformationmessage in operation 1 h-50, the eNB/gNB 1 h-02 may perform an RRCconnection reconfiguration procedure with the UE 1 h-01. First, theeNB/gNB 1 h-02 may transmit an RRCConnectionReconfiguration message tothe UE 1 h-01 (operation 1 h-60). The RRCConnectionReconfigurationmessage may include at least one of configuration information about aDRB to process user data, configuration information about SRB1 and/orSRB2 via which a control message may be transmitted and received, ormeasurement configuration information (measConfig). In response to theRRCConnectionReconfiguration message, the UE 1 h-01 may apply theinformation included in the RRCConnectionReconfiguration message, andthen may transmit an RRCConnectionReconfigurationComplete message to theeNB/gNB 1 h-02 (operation 1 h-65).

The RRCConnectionReconfiguration message in operation 1 h-60 may includea common configuration parameter for configuration of several SCells(Scell Group configuration) at one time or a configuration parameter(SCell configuration) for each of the SCells. When theRRCConnectionReconfiguration message includes a common configurationparameter for several SCells, at least one of the following methods maybe applied.

Method 1: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

Method 2: The RRCConnectionReconfiguration message may include a commonparameter for each SCell group and different parameters for differentSCells in each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCConnectionReconfiguration message may include SCell group        identifiers for identifying the SCell groups.    -   The RRCConnectionReconfiguration message may include a common        parameter for each SCell group (for example, sCellConfigCommon        or sCellGroupCommonConfig).    -   The RRCConnectionReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include an        indicator for indicating delta configuration to apply different        parameters for different SCells in each SCell group. When the        indicator is included in a specific Scell, a common parameter of        an Scell group to which SCells belong. When the indicator is not        included in the specific Scell, only parameters different from        the common parameter of the Scell group may be additionally        included or only the parameter of the specific Scell may be        included.    -   The RRCConnectionReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

The eNB/gNB 1 h-02 may apply CA by indicating a state (activated,dormant, or deactivated state) of each SCell configured in the UE 1 h-01by using a MAC CE (operation 1 h-70).

FIG. 1I illustrates a block diagram of a structure of a UE according toan embodiment of the disclosure.

Referring to FIG. 11I, the UE may include a radio frequency (RF)processor 1 i-10, a baseband processor 1 i-20, a storage 1 i-30, and acontroller 1 i-40. Embodiments are not limited thereto, and the UE mayinclude more or less components than those illustrated in FIG. 1I.

According to an embodiment of the disclosure, the RF processor 1 i-10may perform functions for transmitting and receiving a signal via aradio channel, such as a band conversion, amplification, and the like ofthe signal. In other words, the RF processor 1 i-10 may up-convert abaseband signal provided from the baseband processor 1 i-20, to an RFband signal and transmit the RF band signal through an antenna, anddown-convert an RF band signal received through an antenna, to abaseband signal. For example, the RF processor 1 i-10 may include atransmit filter, a receive filter, an amplifier, a mixer, an oscillator,a digital-to-analog converter (DAC), and an analog-to-digital converter(ADC). Although only a single antenna is illustrated in FIG. 11I, the UEmay include multiple antennas.

The RF processor 1 i-10 may include a plurality of RF chains. The RFprocessor 1 i-10 may perform beamforming. For beamforming, the RFprocessor 1 i-10 may adjust phases and amplitudes of signals transmittedor received through multiple antennas or antenna elements. The RFprocessor 1 i-10 may perform an multiple input multiple output (MIMO)operation and may receive layers (or data of multiple layers) in theMIMO operation. The RF processor 1 i-10 may perform received beamsweeping by appropriately configuring multiple antennas or antennaelements, or may adjust a direction and a beam width of the receivedbeam such that the received beam coordinates with a transmit beam, underthe control of the controller 1 i-40.

The baseband processor 1 i-20 may perform conversion between a basebandsignal and a bitstream based on physical layer specifications of asystem. For example, for data transmission, the baseband processor 1i-20 may generate complex symbols by encoding and modulating a transmitbitstream. For data reception, the baseband processor 1 i-20 mayreconstruct a received bitstream by demodulating and decoding a basebandsignal provided by the RF processor 1 i-10. For example, according to anOFDM scheme, for data transmission, the baseband processor 1 i-20 maygenerate complex symbols by encoding and modulating a transmitbitstream, map the complex symbols to subcarriers, and then configureOFDM symbols by performing inverse fast Fourier transformation (IFFT)and cyclic prefix (CP) insertion. For data reception, the basebandprocessor 1 i-20 may split a baseband signal provided from the RFprocessor 1 i-10, in OFDM symbol units, reconstruct signals mapped tosubcarriers by performing fast Fourier transformation (FFT), and thenreconstruct a received bitstream by demodulating and decoding thesignals.

The baseband processor 1 i-20 and the RF processor 1 i-10 may transmitand receive signals as described above. Each of the baseband processor 1i-20 and the RF processor 1 i-10 may also be called a transmitter, areceiver, a transceiver, or a communicator. At least one of the basebandprocessor 1 i-20 or the RF processor 1 i-10 may include multiplecommunication modules to support multiple different radio accesstechnologies. Also, at least one of the baseband processor 1 i-20 or theRF processor 1 i-10 may include multiple different communication modulesto process signals of different frequency bands. For example, thedifferent radio access technologies may include an LTE network, an NRnetwork, etc. The different frequency bands may include a super highfrequency (SHF) (e.g., 2.5 GHz and 5 GHz) band and a millimeter wave(mmWave) (e.g., 60 GHz) band. The UE may transmit or receive a signal toor from a base station by using the baseband processor 1 i-20 and the RFprocessor 1 i-10, and the signal may include control information anddata.

The storage 1 i-30 may store data for operations of the UE, e.g., basicprograms, application programs, and configuration information Thestorage 1 i-30 may provide the stored data upon request by thecontroller 1 i-40. The storage 1 i-30 may be composed of storage media,such as read-only memory (ROM), random access memory (RAM), hard disks,compact disc (CD)-ROM, and digital versatile discs (DVDs), or acombination of the storage media. The storage 1 i-30 may be composed ofa plurality of memories.

The controller 1 i-40 may control overall operations of the UE. Forexample, the controller 1 i-40 may transmit and receive signals throughthe baseband processor 1 i-20 and the RF processor 1 i-10. Thecontroller 1 i-40 may write and read data to and from the storage 1i-30. To this end, the controller 1 i-40 may include at least oneprocessor. For example, the controller 1 i-40 may include acommunication processor (CP) performing control for communication, andan application processor (AP) controlling an upper layer, such as anapplication program. The controller 1 i-40 may control the UE to performa communication method for supporting the above-described carrieraggregation. At least one of the components included in the UE may beimplemented by using a single chip.

FIG. 1J illustrates a block diagram of a structure of a base stationaccording to an embodiment of the disclosure.

The base station according to an embodiment of the disclosure mayinclude at least one transmission reception point (TRP). Referring toFIG. 1J, the base station may include an RF processor 1 j-10, a basebandprocessor 1 j-20, a communicator 1 j-30, a storage 1 j-40, and acontroller 1 j-50. Embodiments are not limited thereto, and the basestation may include more or less components than those illustrated inFIG. 1J.

The RF processor 1 j-10 may perform functions for transmitting andreceiving a signal via a radio channel, such as a band conversion,amplification, and the like of the signal. In other words, the RFprocessor 1 j-10 may up-convert a baseband signal provided from thebaseband processor 1 i-20, to an RF band signal and transmit the RF bandsignal through an antenna, and down-convert an RF band signal receivedthrough an antenna, to a baseband signal. For example, the RF processor1 j-10 may include a transmitting filter, a receiving filter, anamplifier, a mixer, an oscillator, a DAC, an ADC, or the like. Althoughonly a single antenna is illustrated in FIG. 1J, the RF processor 1 j-10may include multiple antennas. The RF processor 1 j-10 may include aplurality of RF chains. The RF processor 1 j-10 may perform beamforming.For beamforming, the RF processor 1 j-10 may adjust phases andamplitudes of signals transmitted or received through multiple antennasor antenna elements. The RF processor 1 j-10 may perform a DL MIMOoperation by transmitting at least one layer.

The baseband processor 1 j-20 may perform conversion between a basebandsignal and a bitstream based on physical layer specifications of a firstradio access technology. For example, for data transmission, thebaseband processor 1 j-20 may generate complex symbols by encoding andmodulating a transmit bitstream. For data reception, the basebandprocessor 1 j-20 may reconstruct a received bitstream by demodulatingand decoding a baseband signal provided by the RF processor 1 j-10. Forexample, according to an OFDM scheme, for data transmission, thebaseband processor 1 j-20 may generate complex symbols by encoding andmodulating a transmit bitstream, map the complex symbols to subcarriers,and then configure OFDM symbols by performing IFFT and CP insertion. Fordata reception, the baseband processor 1 j-20 may split a basebandsignal provided from the RF processor 1 j-10, in OFDM symbol units,reconstruct signals mapped to subcarriers by performing FFT, and thenreconstruct a received bitstream by demodulating and decoding thesignals. The baseband processor 1 j-20 and the RF processor 1 j-10 maytransmit and receive signals as described above. Accordingly, each ofthe baseband processor 1 j-20 and the RF processor 1 j-10 may also becalled a transmitter, a receiver, a transceiver, a communicator, or awireless communicator. The base station may transmit or receive a signalto or from a base station by using the baseband processor 1 j-20 and theRF processor 1 j-10, and the signal may include control information anddata.

The communicator 1 j-30 may provide an interface for communicating withother nodes in a network. According to an embodiment, the communicator 1j-30 may be a backhaul communicator.

The storage 1 j-40 may store data for operations of a main base station,e.g., basic programs, application programs, and configurationinformation In particular, the storage 1 j-40 may store informationabout bearers allocated for a connected UE, a measurement reporttransmitted from the connected UE, etc. The storage 1 j-40 may storecriteria information used to determine whether to provide or releasemulti-connectivity to or from the UE. The storage 1 j-40 may provide thestored data upon request by the controller 1 j-50. The storage 1 j-40may be composed of storage media, such as ROM, RAM, hard disks, CD-ROM,and DVDs, or a combination of the storage media. The storage 1 j-40 maybe composed of a plurality of memories. The controller 1 j-50 maycontrol overall operations of the base station. For example, thecontroller 1 j-50 may transmit and receive signals through the basebandprocessor 1 j-20 and the RF processor 1 j-10 or through the communicator1 j-30. The controller 1 j-50 may write and read data to and from thestorage 1 j-40. To this end, the controller 1 j-50 may include at leastone processor. Each of the baseband processor 1 j-20 and the RFprocessor 1 j-10 may also be called a transmitter, a receiver, atransceiver, a communicator, or a wireless communicator. The controller1 j-50 may control the base station to perform a communication methodfor supporting the above-described carrier aggregation. At least one ofthe components included in the base station may be implemented by usinga single chip.

FIG. 2A illustrates a diagram of a structure of an LTE system accordingto an embodiment of the disclosure.

Referring to FIG. 2A, a RAN of the LTE system includes evolved node Bs(hereinafter, referred to as eNBs, node Bs (NBs) or base stations) 2a-05, 2 a-10, 2 a-15, and 2 a-20, an MME 2 a-25, and an S-GW 2 a-30. AUE 2 a-35 (also referred to as a terminal) may access an externalnetwork via the eNB 2 a-05, 2 a-10, 2 a-15, or 2 a-20 and the S-GW 2a-30.

In FIG. 2A, the eNB 2 a-05, 2 a-10, 2 a-15, or 1 a-20 may correspond toan existing NB of a UMTS. The eNB 2 a-05, 2 a-10, 2 a-15, or 2 a-20 maybe connected to the UE 2 a-35 through a radio channel and may performcomplex functions compared to the existing NB. In the LTE system, alluser traffic including a real-time service such as VoIP may be providedvia a shared channel. Accordingly, an entity that schedules UEs 2 a-35by gathering state information such as buffer states, available transmitpower states, and channel states of the UEs 2 a-35 may be necessary, andthe eNB 2 a-05, 2 a-10, 2 a-15, or 2 a-20 may operate as the entity.

A single eNB may generally control multiple cells. For example, the LTEsystem may use radio access technology such as OFDM at a bandwidth of 20MHz to achieve a data rate of 100 Mbps. Also, the eNB 2 a-05, 2 a-10, 2a-15, or 2 a-20 may use an AMC scheme to determine a modulation schemeand a channel coding rate in accordance with a channel state of the UE 2a-35. The S-GW 2 a-30 is an entity for providing data bearers and mayconfigure or release the data bearers under the control of the MME 2a-25. The MME 2 a-25 is an entity for performing a mobility managementfunction and various control functions for the UE 2 a-35 and may beconnected to the eNBs 2 a-05, 2 a-10, 2 a-15, and 2 a-20.

FIG. 2B illustrates a diagram of a radio protocol architecture in an LTEsystem, according to an embodiment of the disclosure.

Referring to FIG. 2B, the radio protocol architecture of the LTE systemmay include PDCP layers 2 b-05 and 2 b-40, RLC layers 2 b-10 and 2 b-35,and MAC layers 2 b-15 and 2 b-30 respectively for a UE and an eNB. ThePDCP layer 2 b-05 or 2 b-40 is in charge of IP headercompression/decompression, etc. Main functions of the PDCP layer 2 b-05or 2 b-40 may be summarized as below. Embodiments of the disclosure arenot limited to the following functions.

-   -   Header compression and decompression: ROHC only    -   Transfer of user data    -   In-sequence delivery of upper layer PDUs at PDCP        re-establishment procedure for RLC AM    -   For split bearers in DC (only support for RLC AM): PDCP PDU        routing for transmission and PDCP PDU reordering for reception    -   Duplicate detection of lower layer SDUs at PDCP re-establishment        procedure for RLC AM    -   Retransmission of PDCP SDUs at handover and, for split bearers        in DC, of PDCP PDUs at PDCP data-recovery procedure, for RLC AM    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

The RLC layer 2 b-10 or 2 b-35 may perform, for example, an ARQoperation by reconfiguring PDCP PDUs to appropriate sizes. Mainfunctions of the RLC layer 2 b-10 or 2 b-35 may be summarized as below.Embodiments of the disclosure are not limited to the followingfunctions.

-   -   Transfer of upper layer PDUs    -   Error Correction through ARQ (only for AM data transfer)    -   Concatenation, segmentation and reassembly of RLC SDUs (only for        UM and AM data transfer)    -   Re-segmentation of RLC data PDUs (only for AM data transfer)    -   Reordering of RLC data PDUs (only for UM and AM data transfer)    -   Duplicate detection (only for UM and AM data transfer)    -   Protocol error detection (only for AM data transfer)    -   RLC SDU discard (only for UM and AM data transfer)    -   RLC re-establishment

The MAC layer 2 b-15 or 2 b-30 is connected to multiple RLC layersconfigured for a single UE and may multiplex RLC PDUs into a MAC PDU anddemultiplex the RLC PDUs from the MAC PDU. Main functions of the MAClayer 2 b-15 or 2 b-30 may be summarized as below. Embodiments of thedisclosure are not limited to the following functions.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs belonging to one or        different logical channels into/from transport blocks (TB)        delivered to/from the physical layer on transport channels    -   Scheduling information reporting    -   Error correction through HARQ    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification    -   Transport format selection    -   Padding

A PHY layer 2 b-20 or 2 b-25 may channel-code and modulate upper layerdata into OFDM symbols and transmit the OFDM symbols through a radiochannel, or demodulate OFDM symbols received through a radio channel andchannel-decode and deliver the OFDM symbols to an upper layer.Embodiments of the disclosure are not limited thereto.

FIG. 2C illustrates a diagram of a structure of a next-generation mobilecommunication system, according to an embodiment of the disclosure.

Referring to FIG. 2C, a RAN of the next-generation mobile communicationsystem (e.g., an NR or 5G system) may include a new radio node B(hereinafter, referred to as a NR gNB or an NR base station) 2 c-10 andan NR CN 2 c-05. An NR UE or UE 2 c-15 may access an external networkvia the NR gNB 2 c-10 and the NR CN 2 c-05.

In FIG. 2C, the NR gNB 2 c-10 may correspond to an eNB of an existingLTE system. The NR gNB 2 c-10 is connected to the NR UE 2 c-15 throughradio channels and may provide superior services compared to an existingNB. In the next-generation mobile communication system, all user trafficmay be provided via a shared channel. Accordingly, an entity thatschedules UEs by gathering state information such as buffer states,available transmit power states, and channel states of the UEs may benecessary, and the NR gNB 2 c-10 may operate as the entity. A single NRgNB may generally control multiple cells. In the next-generation mobilecommunication system, a bandwidth greater than a current maximumbandwidth may be used to achieve an ultrahigh data rate compared to acurrent LTE system. OFDM may be used as radio access technology, andbeamforming technology may be additionally used. According to anembodiment, the NR gNB 2 c-10 may use an AMC scheme to determine amodulation scheme and a channel coding rate in accordance with a channelstate of the UE.

The NR CN 2 c-05 may perform functions such as mobility support, bearersetup, and QoS setup. The NR CN 2 c-05 is an entity for performing amobility management function and various control functions for the UEmay be connected to multiple NR gNBs 2 c-10. The next-generation mobilecommunication system may cooperate with the existing LTE system, and theNR CN 2 c-05 may be connected to an MME 2 c-25 through a networkinterface. The MME 2 c-25 may be connected to an eNB 2 c-30 being anexisting base station.

FIG. 2D illustrates a diagram of a radio protocol architecture of anext-generation mobile communication system, according to an embodimentof the disclosure.

Referring to FIG. 2D, the radio protocol architecture of thenext-generation mobile communication system may include NR SDAP layers 2d-01 and 2 d-45, NR PDCP layers 2 d-05 and 2 d-40, NR RLC layers 2 d-10and 2 d-35, NR MAC layers 2 d-15 and 2 d-30, and NR PHY layers 2 d-20and 2 d-25 respectively for a UE and an NR gNB.

According to an embodiment, main functions of the NR SDAP layer 2 d-01or 2 d-45 may include some of the following functions. Embodiments ofthe disclosure are not limited to the following functions.

-   -   Transfer of user plane data    -   Mapping between a QoS flow and a DRB for both DL and UL    -   Marking QoS flow ID in both DL and UL packets    -   Reflective QoS flow to DRB mapping for the UL SDAP PDUs

With respect to an SDAP layer, the UE may receive, via an RRC message,settings on whether to use a header of the SDAP layer or use a functionof the SDAP layer for each PDCP layer, each bearer, or each logicalchannel. When an SDAP header is configured, the UE may instruct anon-access stratum (NAS) reflective QoS 1-bit indicator and an accessstratum (AS) reflective QoS 1-bit indicator of the SDAP header to updateor reconfigure mapping information regarding the data bearer and the QoSflow of UL and DL. The SDAP header may include QoS flow ID indicatingQoS. According to an embodiment, QoS information may be used as dataprocessing priority information, scheduling information, etc. forsupporting a smooth service.

According to an embodiment, main functions of the NR PDCP layer 2 d-05or 2 d-40 may include some of the following functions. Embodiments ofthe disclosure are not limited to the following functions.

-   -   Header compression and decompression: ROHC only    -   Transfer of user data    -   In-sequence delivery of upper layer PDUs    -   Out-of-sequence delivery of upper layer PDUs    -   PDCP PDU reordering for reception    -   Duplicate detection of lower layer SDUs    -   Retransmission of PDCP SDUs    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

According to an embodiment, a reordering function of the NR PDCP layer 2d-05 or 2 d-40 may denote a function of reordering PDCP PDUs receivedfrom a lower layer, based on a PDCP SN. The reordering function of theNR PDCP layer 2 d-05 or 2 d-40 may include at least one of a function ofdelivering the reordered data to an upper layer in order, a function ofimmediately delivering the reordered data without considering an order,a function of recording missing PDCP PDUs by reordering the PDCP PDUs, afunction of reporting a status of the missing PDCP PDUs to atransmitter, or a function of requesting to retransmit the missing PDCPPDUs.

According to an embodiment, main functions of the NR RLC layer 2 d-10 or2 d-35 may include some of the following functions. Embodiments of thedisclosure are not limited to the following functions.

-   -   Transfer of upper layer PDUs    -   In-sequence delivery of upper layer PDUs    -   Out-of-sequence delivery of upper layer PDUs    -   Error Correction through ARQ    -   Concatenation, segmentation and reassembly of RLC SDUs    -   Re-segmentation of RLC data PDUs    -   Reordering of RLC data PDUs    -   Duplicate detection    -   Protocol error detection    -   RLC SDU discard    -   RLC re-establishment

According to an embodiment, in-sequence delivery of the NR RLC layer 2d-10 or 2 d-35 may denote a function of delivering RLC SDUs receivedfrom a lower layer, to an upper layer in order. When an RLC SDU issegmented into multiple RLC SDUs and received, the in-sequence deliveryof the NR RLC layer 2 d-10 or 2 d-35 may include a function ofreassembling the multiple RLC SDUs and delivering the RLC SDUs.

The in-sequence delivery of the NR RLC layer 2 d-10 or 2 d-35 mayinclude at least one of a function of reordering received RLC PDUs on anRLC SN or PDCP SN basis, a function of recording missing RLC PDUs byreordering the RLC PDUs, a function of reporting a status of the missingRLC PDUs to a transmitter, or a function of requesting to retransmit themissing RLC PDUs.

According to an embodiment, the in-sequence delivery of the NR RLC layer2 d-10 or 2 d-35 may include a function of delivering only RLC SDUsprevious to a missing RLC SDU, to the upper layer in order, when themissing RLC SDU exists. According to an embodiment, the in-sequencedelivery of the NR RLC layer 2 d-10 or 2 d-35 may include a function ofdelivering all RLC SDUs received before a timer is started, to the upperlayer in order, when a certain timer is expired although a missing RLCSDU exists. The in-sequence delivery of the NR RLC layer 2 d-10 or 2d-35 may include a function of delivering all RLC SDUs received up to acurrent time, to the upper layer in order, when a certain timer isexpired although a missing RLC SDU exists. Embodiments of the disclosureare not limited thereto.

According to an embodiment, the NR RLC layer 2 d-10 or 2 d-35 mayprocess the RLC PDUs in order of reception regardless of sequencenumbers and deliver the RLC PDUs to the NR PDCP layer 2 d-05 or 2 d-40(Out-of sequence delivery).

According to an embodiment, when the NR RLC layer 2 d-10 or 2 d-35receives segments, the NR RLC layer 2 d-10 or 2 d-35 may reconfigure thesegments received later or stored in a buffer, into a whole RLC PDU anddeliver the whole RLC PDU to the NR PDCP layer 2 d-05 or 2 d-40.According to an embodiment, the NR RLC layer 2 d-10 or 2 d-35 may nothave a concatenation function, and the concatenation function may beperformed by the NR MAC layer 2 d-15 or 2 d-30 or be replaced with amultiplexing function of the NR MAC layer 2 d-15 or 2 d-30.

According to an embodiment, out-of-sequence delivery of the NR RLC layer2 d-10 or 2 d-35 may denote a function of delivering RLC SDUs receivedfrom a lower layer, immediately to an upper layer out of an order. Theout-of-sequence delivery of the NR RLC layer 2 d-10 or 2 d-35 mayinclude a function of reassembling multiple RLC SDUs segmented from anRLC SDU and delivering the RLC SDU when the segmented RLC SDUs arereceived. The out-of-sequence delivery of the NR RLC layer 2 d-10 or 2d-35 may include a function of storing RLC SNs or PDCP SNs of receivedRLC PDUs and recording missing RLC PDUs by ordering the RLC PDUs.

According to an embodiment, the NR MAC layer 2 d-15 or 2 d-30 may beconnected to multiple NR RLC layers 2 d-10 or 2 d-35 configured for asingle UE, and main functions of the NR MAC layer 2 d-15 or 2 d-30 mayinclude some of the following functions. Embodiments of the disclosureare not limited to the following functions.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs    -   Scheduling information reporting    -   Error correction through HARQ    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification    -   Transport format selection    -   Padding

According to an embodiment, the NR PHY layer 2 d-20 or 2 d-25 maychannel-code and modulate upper layer data into OFDM symbols andtransmit the OFDM symbols through a radio channel, or demodulate OFDMsymbols received through a radio channel and channel-decode and deliverthe OFDM symbols to an upper layer. However, embodiments are not limitedthereto.

FIG. 2E illustrates a diagram for describing a procedure in which a UEnot supporting an idle mode measurement establishes an RRC connectionwith a gNB and switches an RRC idle mode to an RRC connected mode, and aprocedure in which the gNB configures CA for the UE, according to anembodiment of the disclosure.

The UE according to an embodiment of the disclosure may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in the RRC idle mode. However, the UE does not report, to the gNB,results of separately measuring one or more frequencies in the RRC idlemode. In other words, after the UE transits from the RRC idle mode tothe RRC connected mode, the UE may measure one or more frequencies,based on measurement configuration information (measConfig) set in anRRCReconfiguration message, and, when a set condition is satisfied, maytransmit a MeasurementReport message to the gNB.

Referring to FIG. 2E, a UE 2 e-01 may establish an RRC connection with agNB 2 e-02 and thus may be in the RRC connected mode (operation 2 e-05).When the UE 2 e-01 that transmits or receives data in the RRC connectedmode does not transmit or receive data for a certain reason or for acertain time, the gNB 2 e-02 may transmit an RRCRelease message notincluding suspended configuration information (suspendConfig) to the UE2 e-01 such that the UE 2 e-01 switches to the RRC idle mode (operation2 e-10). The UE 2 e-01 in the RRC idle mode may receive systeminformation by searching for and camping on a suitable cell, via a cellselection procedure and/or a cell reselection procedure (operation 2e-15).

The UE 2 e-01 may perform a random access procedure in order toestablish an RRC connection with the gNB 2 e-02. When random access istriggered (operation 2 e-16), the UE 2 e-01 may select a PRACH occasionand transmit a Random Access Preamble to the gNB 2 e-02 (operation 2e-20). In response to the Random Access Preamble, the gNB 2 e-02 maytransmit an RAR message to the UE 2 e-01 (operation 2 e-25). The UE 2e-01 in the RRC idle mode may establish an inverse directiontransmission synchronization with the gNB 2 e-02 through operations 2e-20 and 2 e-25.

The UE 2 e-01 in the RRC idle mode may perform an RRC connectionestablishment procedure with the gNB 2 e-02. First, the UE 2 e-01 maytransmit a RRCSetupRequest message to the gNB 2 e-02 (operation 2 e-30).The RRCSetupRequest message may include an identity of the UE 2 e-01, anestablishment cause for establishing an RCC connection, or the like. Inresponse to the RRCSetupRequest message, the gNB 2 e-02 may transmit anRRCSetup message to the UE 2 e-01 (operation 2 e-35). The RRCSetupmessage may include radio bearer configuration information(radioBearerConfig), master cell group configuration information(masterCellGroup), etc. In detail, the radio bearer configurationinformation and the master cell group configuration information withinthe RRCSetup message may include information accompanied by SRB1connection, RLC bearer configuration information about SRB1, MAC cellgroup configuration information (mac-CellGroupConfig), physical cellgroup configuration information (physicalCellGroupConfig), etc. Inresponse to the RRCSetup message, the UE 2 e-01 may apply theinformation included in the RRCSetup message and may switch the RRC idlemode to the RRC connected mode (operation 2 e-36). The UE 2 e-01 in theRRC connected mode may transmit a RRCSetupComplete message to the gNB 2e-02 through SRB1 (operation 2 e-40).

When the RRC connection establishment procedure is successfullyperformed, the gNB 2 e-02 may perform an RRC connection reconfigurationprocedure with the UE 2 e-01. First, the gNB 2 e-02 may transmit anRRCReconfiguration message to the UE 2 e-01 (operation 2 e-45). TheRRCReconfiguration message may include at least one of radio bearerconfiguration information (radioBearerConfig), master cell groupconfiguration information (masterCellGroup), or measurementconfiguration information (measConfig). In response to theRRCReconfiguration message, the UE 2 e-01 may apply the informationincluded in the RRCReconfiguration message, and then may transmit anRRCReconfigurationComplete message to the gNB 2 e-02 (operation 2 e-50).

When the RRCReconfiguration message includes the measConfig in operation2 e-45, the UE 2 e-01 in the RRC connected mode may perform measurementby applying the measConfig. When measurement reporting is triggered(operation 2 e-51), the UE 2 e-01 may transmit a MeasurementReportmessage to the gNB 2 e-02 (operation 2 e-55).

When the gNB 2 e-02 successfully receives the MeasurementReport message,the gNB 2 e-02 may perform an RRC connection reconfiguration procedureto configure CA for the UE 2 e-01 in the RRC connected mode. CAaccording to an embodiment of the disclosure means more transmitting andreceiving data between a UE and a BS through an additional carrier orsecondary cells or serving cells (SCells). First, the gNB 2 e-02 maytransmit an RRCReconfiguration message to the UE 2 e-01 (operation 2e-60). The RRCReconfiguration message may include configurationinformation (Scell configuration) about at least one SCell. For example,the Scell configuration may include a list of SCells to be added ormodified (sCellToAddModList) and/or a list of configured SCells to bereleased (sCellToReleaseList), each of which is an IE. When the UE 2e-01 successfully receives the RRCReconfiguration message, the UE 2 e-01may apply the Scell configuration and then transmit anRRCReconfigurationComplete message to the gNB 2 e-02 (operation 2 e-65).The gNB 2 e-02 may apply CA by indicating a state (activated ordeactivated state) of each SCell configured in the UE 2 e-01 by using aMAC CE (operation 2 e-70).

FIG. 2F illustrates a diagram for describing a procedure in which a UEnot supporting an idle mode measurement establishes an RRC connectionwith a gNB and switches an RRC inactive mode to an RRC connected mode,and a procedure in which the gNB configures CA for the UE, according toan embodiment of the disclosure.

The UE according to an embodiment of the disclosure may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in an RRC inactive mode. However, the UE does not report, to thegNB, results of separately measuring one or more frequencies in the RRCinactive mode. In other words, after the UE transits from the RRCinactive mode to the RRC connected mode, the UE may measure one or morefrequencies, based on measurement configuration information (measConfig)set in an RRCResume message or an RRCReconfiguration message, and, whena set condition is satisfied, may transmit a MeasurementReport messageto the gNB.

Referring to FIG. 2F, a UE 2 f-01 may establish an RRC connection with agNB 2 f-02 and thus may be in the RRC connected mode (operation 2 f-05).When the UE 2 f-01 that transmits or receives data in the RRC connectedmode does not transmit or receive data for a certain reason or for acertain time, the gNB 2 f-02 may transmit an RRCRelease messageincluding suspended configuration information (suspendConfig) to the UE2 f-01 such that the UE 2 f-01 switches to the RRC inactive mode(operation 2 f-10). The UE 2 f-01 in the RRC inactive mode may receivesystem information by searching for and camping on a suitable cell, viaa cell selection procedure and/or a cell reselection procedure(operation 2 f-15).

The UE 2 f-01 may perform a random access procedure in order toestablish an RRC connection with the gNB 2 f-02. When random access istriggered (operation 2 f-16), the UE 2 f-01 may select a PRACH occasionand transmit a Random Access Preamble to the gNB 2 f-02 (operation 2f-20). In response to the Random Access Preamble, the gNB 2 f-02 maytransmit an RAR message to the UE 2 f-01 (operation 2 f-25). The UE 2f-01 in the RRC inactive mode may establish an inverse directiontransmission synchronization with the gNB 2 f-02 through operations 2f-20 and 2 f-25.

The UE 2 f-01 in the RRC inactive mode may perform an RRC connectionresume procedure with the gNB 2 f-02. First, the UE 2 f-01 may transmitan RRCResumeRequest message or an RRCResumeRequest1 message to the gNB 2f-02 (operation 2 f-30). According to an embodiment, theRRCResumeRequest message or the RRCResumeRequest1 message may include,for example, a UE identifier (resumeIdentity), resume encryptioninformation (resumeMAC-I), and a cause (resumeCause) for resuming an RRCconnection, which are used by a gNB to retrieve a terminal context. Inresponse to the RRCResumeRequest message or the RRCResumeRequest1message, the gNB 2 f-02 may transmit an RRCResume message to the UE 2f-01 (operation 2 f-35). The RRCResumeRequest message or theRRCResumeRequest1 message may include radio bearer configurationinformation (radioBearerConfig), master cell group configurationinformation (masterCellGroup), measurement configuration information(measConfig), etc. In detail, the radio bearer configuration informationand the master cell group configuration information within theRRCResumeRequest message or the RRCResumeRequest1 message may include,but are not limited to, configuration information of an SRB and DRBsthat resume, RLC bearer configuration information about the SRB and theDRBs, MAC cell group configuration information (mac-CellGroupConfig),physical cell group configuration information (physicalCellGroupConfig),etc. In response to the RRCSetup message, the UE 2 f-01 may apply theinformation included in the RRCResumeRequest message or theRRCResumeRequest1 message and may switch the RRC inactive mode to theRRC connected mode (operation 2 f-36). The UE 2 f-01 in the RRCconnected mode may transmit a RRCResumeComplete message to the gNB 2f-02 through SRB1 (operation 2 f-40).

When the RRCResume message includes the measConfig in operation 2 f-35,the UE 2 f-01 in the RRC connected mode may perform measurement byapplying the measConfig. When measurement reporting is triggered(operation 2 f-51), the UE 2 f-01 may transmit a MeasurementReportmessage to the gNB 2 f-02 (operation 2 f-55). According to anembodiment, the UE 2 f-01 may perform the above procedure withoutperforming operations 2 f-45 and 2 f-50.

When the RRC connection resume procedure is successfully performed, thegNB 2 f-02 may perform an RRC connection reconfiguration procedure withthe UE 2 f-01. First, the gNB 2 f-02 may transmit an RRCReconfigurationmessage to the UE 2 f-01 (operation 2 f-45). The RRCReconfigurationmessage may include at least one of radio bearer configurationinformation (radioBearerConfig), master cell group configurationinformation (masterCellGroup), or measurement configuration information(measConfig). In response to the RRCReconfiguration message, the UE 2f-01 may apply the information included in the RRCReconfigurationmessage, and then may transmit an RRCReconfigurationComplete message tothe gNB 2 f-02 (operation 2 f-50).

When the RRCReconfiguration message includes the measConfig in operation2 f-45, the UE 2 f-01 in the RRC connected mode may perform measurementby applying the measConfig. When measurement reporting is triggered(operation 2 f-51), the UE 2 f-01 may transmit a MeasurementReportmessage to the gNB 2 f-02 (operation 2 f-55).

When the gNB 2 f-02 successfully receives the MeasurementReport message,the gNB 2 f-02 may perform an RRC connection reconfiguration procedureto configure CA for the UE 2F-01 in the RRC connected mode. CA accordingto an embodiment of the disclosure means more transmitting and receivingdata between a UE and a BS through an additional carrier or secondarycells or serving cells (SCells). First, the gNB 2 f-02 may transmit anRRCReconfiguration message to the UE 2 f-01 (operation 2 f-60). TheRRCReconfiguration message may include configuration information (Scellconfiguration) about at least one SCell. For example, the Scellconfiguration may include a list of SCells to be added or modified(sCellToAddModList) and/or a list of configured SCells to be released(sCellToReleaseList), each of which is an IE. When the UE 2 f-01successfully receives the RRCReconfiguration message, the UE 2 f-01 mayapply the Scell configuration and then transmit anRRCReconfigurationComplete message to the gNB 2 f-02 (operation 2 f-65).The gNB 2 f-02 may apply CA by indicating a state (activated ordeactivated state) of each SCell configured in the UE 2 f-01 by using aMAC CE (operation 2 f-70).

FIG. 2G illustrates a diagram for describing a procedure in which a UEsupporting an idle mode measurement releases an RRC connection with agNB and switches an RRC connected mode to an RRC idle mode, and a methodin which the gNB provides idle mode measurement configurationinformation to the UE, according to an embodiment of the disclosure.

The UE according to an embodiment of the disclosure may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in the RRC idle mode. The UE may measure several frequencies in theRRC idle mode and may store results of the measurements, separately. Tothis end, the gNB may transmit, to the UE in the RRC connected mode, anRRCRelease message including measurement configuration information(measIdleConfig) that is available in the RRC idle mode by the UE.Alternatively, the gNB may broadcast, to the UE in the RRC idle mode,system information (e.g., SIB5 or a new SIBx) including measurementconfiguration information (measIdleConfigSIB) that is available in theRRC idle mode by the UE. The UE in the RRC idle mode may measure atleast one frequency, based on the measurement configuration informationincluded in the RRCRelease message or the system information. When thegNB transmits a UEInformationRequest message to the UE that hastransited from the RRC idle mode to the RRC connected mode in order torequest a measurement result, the UE may transmit to the gNB aUEInformationResponse message including a result of a measurementperformed in the RRC idle mode. This may delay application of existingCA by a long time.

Referring to FIG. 2G, a UE 2 g-01 may establish an RRC connection withan eNB/gNB 2 g-02 and thus may be in the RRC connected mode (operation 2g-05). When the UE 2 g-01 that transmits or receives data in the RRCconnected mode does not transmit or receive data for a certain reason orfor a certain time, the eNB/gNB 2 g-02 may transmit an RRCReleasemessage not including suspended configuration information(suspendConfig) to the UE 2 g-01 such that the UE 2 g-01 switches to theRRC idle mode (operation 2 g-10). The RRCRelease message may furtherinclude measurement configuration information available in the RRC idlemode (measIdleConfig). The measIdleConfig being an IE may include atleast one of the following parameters.

-   -   A carrier frequency list used for measurement by the UE 2 g-01        in the RRC idle mode (measIdleCarrierList) The measIdleCarrier        List may include one or more pieces of information        (measIdleCarrier) about each carrier frequency.    -   Each measIdleCarrier include at least one of the following        pieces of information. Embodiments of the disclosure are not        limited to the following example.    -   dl-CarrierFreq: An absolute radio frequency channel number value        (ARFCN-Value) representing the center frequency of a        synchronization signal block (hereinafter, an SS Block) of        neighboring cells may be included. The UE 2 g-01 may apply        reference signal measurement timing configuration of neighboring        cells, based on the information dl-CarrierFreq, or may perform        neighboring cell measurement.    -   nrofSS-BlocksToAverage: The number of SS/PBCH blocks that are        used to derive a cell measurement value. The UE 2 g-01 may        derive a cell measurement value by taking an average of SS/PBCH        measurement values by applying the signaled value. When the        information nrofSS-BlocksToAverage is not signaled, the UE 2        g-01 may derive a cell measurement value, based on a SS/PBCH        block providing a greatest signal intensity.    -   absThreshSS-BlocsConsolidation: A threshold that is used to        consolidate measurement results of the SS/PBCH blocks. The UE 2        g-01 may use, in the cell measurement value, an SS/PBCH block        signal intensity that is greater than a signaled        absThreshSS-BlocsConsolidation value. When the information        absThreshSS-BlocsConsolidation is not signaled, the UE 2 g-01        may derive a cell measurement value, based on a SS/PBCH block        providing a greatest signal intensity.    -   smtc: Measurement timing configuration information for        inter-frequency measurement or intra-frequency measurement may        be included. In detail, the information smtc may mean period and        offset information of a measurement time interval for receiving        an SS/PBCH block, and duration information of the measurement        time interval. An ASN. 1 structure of smtc is as shown in Table        1 below.

TABLE 1 SSB-MTC information element ASN1START TAG-SSB-MTC-START SSB-MTC::= SEQUENCE { periodicityAndOffset CHOICE { sf5 INTEGER (0..4), sf10INTEGER (0..9), sf20 INTEGER (0..19), sf40 INTEGER (0..39), sf80 INTEGER(0..79), sf160  INTEGER (0..159) }, duration  ENUMERATED { sf1, sf2,sf3, sf4, sf5 } }

The UE 2 g-01 may set a reference signal measurement timing via thesignaled value.

-   -   ssbSubcarrierSpacing: A sub-carrier spacing between SSBs may be        included. For example, in the case of a frequency band that is        less than 6 GHz, a 15 or 30 kHz value may be signaled, and, in        the case of a frequency band that is greater than 6 GHz, a 120        or 240 kHz value may be signaled.    -   deriveSSB-IndexFromCell: An indicating value indicating timing        information that the UE 2 g-01 may/should use to derive the        index of an SS block that is transmitted by a neighboring cell        or serving cell existing in a signaled center frequency may be        included. For example, when a deriveSSB-IndexFromCell value is        signaled or set as TRUE, the UE 2 g-01 may derive the index of        an SS block of all of the neighboring cells existing in the        center frequency by applying timing information of any cell        detected in the center frequency. This may also be equally        applied to a case where the center frequency is a serving        frequency, Because, due to a cell reselection procedure, the        center frequency of the UE 2 g-01 performing idle mode        measurement may be a serving frequency or an inter-frequency.        Alternatively, the UE 2 g-01 may apply a system frame number        (SFN) and a frame boundary alignment to all of the cells        existing in the center frequency.    -   reportQuantities: An indicator indicating whether the UE 2 g-01        reports result values of cells measured through idle mode        measurement with a reference signal received power (RSRP) or a        reference signal received quantity (RSRQ) or with both of the        RSRP and the RSRQ may be included.    -   reportQuantityCell: The result values of the cells measured by        the UE 2 g-01 through idle mode measurement may be included. In        this case, the UE 2 g-01 may report, to the eNB/gNB 2 g-02, the        result values of the cells measured by the UE 2 g-01 through        idle mode measurement with the RSRP or the RSRQ or with both of        the RSRP and the RSRQ.    -   reportQuantityRsIndexes: An indicator indicating whether the UE        2 g-01 reports information measured for each reference signal        (RS) index through idle mode measurement with the RSRP or the        RSRQ or with both of the RSRP and the RSRQ may be included. The        information reportQuantityRsIndexes may be indicated when a beam        level management is efficient during Scell configuration.    -   maxNrofRS-IndexesToReport: A value representing how many RS        indexes at maximum the UE 2 g-01 reports to the eNB/gNB 2 g-02,        based on idle mode measurement, may be included. The information        maxNrofRS-IndexesToReport may be indicated when a beam level        management is efficient during Scell configuration.    -   includeBeamMeasurements: An indicator indicating that a beam        measurement result is to be included may be included. For        example, when reportQuantityRS-Indexes is set as TRUE for each        SS/PBCH block index, the UE 2 g-01 may report a measurement        value to the eNB/gNB 2 g-02, based on SS/PBCH. The information        includeBeamMeasurements may be indicated when a beam level        management is efficient during Scell configuration.    -   validityArea: A cell list on which the UE 2 g-01 is requested to        perform idle mode measurement and report a result of the idle        mode measurement may be included.    -   measCellList: A cell list on which the UE 2 g-01 is requested to        perform idle mode measurement and report a result of the idle        mode measurement may be included.    -   quantityThreshold: A threshold of the RSRP or RSRQ based on        which the UE 2 g-01 may determine whether to report cells        measured via idle mode measurement may be included.        Alternatively, respective thresholds may be included for the        RSRP and the RSRQ.    -   measIdleCarrierList may be signaled for each radio access        technology. For example, measIdleCarrierList may include        measIdleCarrierListEUTRA and measIdleCarrierListNR.    -   A value representing a duration while the UE 2 g-01 performs        measurement in the RRC idle mode (measIdleDuration)

According to an embodiment, the measIdleDuration may represent a timerT311 value or a new timer T3xx value.

The UE 2 g-01 may perform idle mode measurement after the UE 2 g-01receives the RRCRelease message and before the measIdleDuration expires.

-   -   measIdleDuration may be signaled for each radio access        technology or regardless of radio access technologies. For        example, measIdleDuration may be divided into        measIdleDurationEUTRA and measIdleDurationNR and signaled, or        may be signaled as a single value to be commonly applied.

When the RRCRelease message includes measIdleConfig in operation 2 g-10,the UE 2 g-01 may delete VarMeasIdleConfig and VarMeasIdleReport beingUE variables. The UE may store, in the measIdleConfig, the valuerepresenting the duration while the UE performs measurement in the RRCidle mode (e.g., measIdleDuration), and may drive a timer by applyingthe value representing the duration while the UE performs measurement inthe RRC idle mode. When the RRCRelease message includes the carrierfrequency list used for measurement by the UE in the RRC idle mode, theUE 2 g-01 may store the carrier frequency list and perform idle modemeasurement while a timer is operating in supportable carriers, based onthe stored carrier frequency list (operation 2 g-16). When theRRCRelease message does not include the carrier frequency list used formeasurement by the UE in the RRC idle mode, the UE 2 g-01 may receivesystem information by searching for and camping on a suitable cell, viaa cell selection procedure and/or a cell reselection procedure(operation 2 g-15). When a carrier frequency list measIdleConfigSIB usedfor measurement in the RRC idle mode is included in the received systeminformation, the UE 2 g-01 may store the received measIdleConfigSIBwhile the on-going operation of the timer continues, or may replace thecarrier frequency list within the UE 2 g-01, based on the receivedmeasIdleConfigSIB, and perform idle mode measurement while the timer isoperating in supportable carriers, based on the carrier frequency list(operation 2 g-15). The measIdleConfigSIB according to an embodiment mayinclude some or all of the parameters included in the above-describedmeasIdleConfig.

When system information that is broadcast by a target cell does notinclude the measIdleConfigSIB through a cell reselection procedure, theUE 2 g-01 may stop the on-going idle mode measurement.

In operation 2 g-16, the UE 2 g-01 may perform measurement by deriving atiming of an SS/PBCH block, based on an SFN and a subframe of a certaincell, by using the smtc received from the eNB/gNB 2 g-02 and a certainequation. The certain equation is expressed as follows. SMTC issubstituted into the equation below. An SFN including a measurement timeinterval of each SS/PBCH block satisfies the following equation.SFN mod T=(FLOOR (Offset/10))

When a period is greater than 5 subframes, a subframe by which a firstSS/PBCH block of the interval satisfies the following equation.subframe=Offset mod 10Otherwise,subframe=Offset or (Offset+5)

Herein, T means CEIL(Periodicity/10).

A UE according to an embodiment of the disclosure may measure aplurality of frequencies in the RRC idle mode and may store results ofthe measurements. In this case, a serving cell or neighboring cells mayhave different SFNs and different subframe timings. Thus, the UE 2 g-01needs to determine the SFNs and the subframes of which serving cell orneighboring cells are based on to derive the timing of the SS/PBCHblock. According to the disclosure, the serving cell or neighboringcells serving as a basis are determined using at least one of thefollowing methods. Embodiments of the disclosure are not limited to thefollowing examples.

Option 1) When the RRCRelease message (operation 2 g-10) includes smtc,the UE may derive the timing of the SS/PBCH block for a cell that hasreceived the RRCRelease message, based on the smtc information. On theindicated dl-CarrierFreq in the RRCRelease message, the UE shall notconsider SS/PBCH block transmission in subframes outside the SMTCoccasion for radio resource measurements (RRMs) based on SS/PBCH blocks.

Option 2) When the RRCRelease message (operation 2 g-10) includes smtc,the UE may derive the timing of the SS/PBCH block for a serving cell,based on the smtc information. On the indicated dl-CarrierFreq in theRRCRelease message, the UE shall not consider SS/PBCH block transmissionin subframes outside the SMTC occasion for RRMs based on SS/PBCH blocks.

Option 3) When the RRCRelease message (operation 2 g-10) includes smtc,the UE may derive the timing of the SS/PBCH block for a cell list(measCellList or validityArea) included in the RRCRelease message, basedon the smtc information. On the indicated dl-CarrierFreq in theRRCRelease message, the UE shall not consider SS/PBCH block transmissionin subframes outside the SMTC occasion for RRMs based on SS/PBCH blocks.

Option 4) When the system information (operation 2 g-15) includes smtc,the UE may derive the timing of the SS/PBCH block for a cell list(measCellList or validityArea) included in the system information, basedon the smtc information. For example, for a cell included in a servingfrequency, the UE may apply smtc information included in SIB2, or, for acell included in an inter-frequency, the UE may apply smtc informationincluded in SIB4. On the indicated dl-CarrierFreq in the RRCReleasemessage, the UE shall not consider SS/PBCH block transmission insubframes outside the SMTC occasion for RRMs based on SS/PBCH blocks.

The UE may receive an SS/PBCH block during the derived measurement timeinterval, and may perform RSRP, RSRQ, etc. corresponding to the receivedSS/PBCH block.

The UE 2 g-01 may perform a random access procedure in order toestablish an RRC connection with the eNB/gNB 2 g-02. When random accessis triggered (operation 2 g-18), the UE 2 g-01 may select a PRACHoccasion and transmit a Random Access Preamble to the eNB/gNB 2 g-02(operation 2 g-20). In response to the Random Access Preamble, theeNB/gNB 2 g-02 may transmit an RAR message to the UE 2 g-01 (operation 2g-25). The UE 2 g-01 in the RRC idle mode may establish an inversedirection transmission synchronization with the eNB/gNB 2 g-02 throughoperations 2 g-20 and 2 g-25.

The UE 2 g-01 in the RRC idle mode may perform an RRC connectionestablishment procedure with the eNB/gNB 2 g-02. First, the UE 2 g-01may transmit a RRCSetupRequest message to the eNB/gNB 2 g-02 (operation2 g-30). The RRCSetupRequest message may include an identity of the UE 2g-01, an establishment cause for establishing an RCC connection, or thelike. In response to the RRCSetupRequest message, the eNB/gNB 2 g-02 maytransmit an RRCSetup message to the UE 2 g-01 (operation 2 g-35). TheRRCSetup message may include radio bearer configuration information(radioBearerConfig), master cell group configuration information(masterCellGroup), etc. In detail, the radio bearer configurationinformation and the master cell group configuration information mayinclude information accompanied by SRB1 connection, RLC bearerconfiguration information about SRB1, MAC cell group configurationinformation (mac-CellGroupConfig), physical cell group configurationinformation (physicalCellGroupConfig), etc. In response to the RRCSetupmessage, the UE 2 g-01 may apply the information and may switch the RRCidle mode to the RRC connected mode (operation 2 g-36). When the systeminformation received in operation 2 g-15 includes an indicator(idleModeMeasurements) indicating that the eNB/gNB 2 g-02 is able toprocess idle mode measurement of the UE 2 g-01, and theVarMeasIdleReport as a UE variable includes idle mode measurementinformation by performing idle mode measurement in operation 2 g-16, theUE 2 g-01 switched to the RRC connected mode may include, in anRRCSetupComplete message, an indicator (idleMeasAvailable) indicatingthat an idle mode measurement report is possible. The UE 2 g-01 may stopwhen the timer (for example, T311 or T3xx) keeps operating. The UE 2g-01 in the RRC connected mode may transmit the RRCSetupComplete messageto the eNB/gNB 2 g-02 through SRB1 (operation 2 g-40).

When the RRC connection establishment procedure is successfullyperformed, the eNB/gNB 2 g-02 may perform an RRC connectionreconfiguration procedure with the UE 2 g-01. First, the eNB/gNB 2 g-02may transmit an RRCReconfiguration message to the UE 2 g-01 (operation 2g-45). The RRCReconfiguration message may include at least one of radiobearer configuration information (radioBearerConfig), master cell groupconfiguration information (masterCellGroup), or measurementconfiguration information (measConfig). In response to theRRCReconfiguration message, the UE 2 g-01 may apply the informationincluded in the RRCReconfiguration message, and then may transmit anRRCReconfigurationComplete message to the eNB/gNB 2 g-02 (operation 2g-50).

When the RRCSetupComplete message includes the indicator(idleMeasAvailable) indicating that an idle mode measurement report ispossible, in operation 2 g-40, the eNB/gNB 2 g-02 may perform a UEinformation procedure with the UE 2 g-01. The UE information proceduremay be immediately performed without performing the above-described RRCconnection reconfiguration procedure (including operations 2 g-45 and 2g-50). The eNB/gNB 2 g-02 may transmit, to the UE 2 g-01 in the RRCconnected mode, a UEInformationRequest message including an indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC idle mode (operation 2 g-55). When security issuccessfully configured, the UE 2 g-01 that has received theUEInformationRequest message may perform the following processes.

1> When the UEInformationRequest message includes the indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC idle mode and the UE 2 g-01 has stored theVarMeasIdleReport,

2> measResultListIdle included in a UEInformationResponse message is setas a measReportIdle value (or an idleMeasReport value) included in theVarMeasIdleReport.

2> When it is confirmed by lower layers that the UEInformationResponsemessage was transmitted successfully, the VarMeasIdleReport isdiscarded.

1> The UEInformationResponse message is submitted to the lower layersvia the SRB1. The UE 2 g-01 may transmit, to the eNB/gNB 2 g-02, theUEInformationReponse message including a list (measResultListIdle) ofresults of the measurements performed in the RRC idle mode (operation 2g-60).

In the above description, the measResultListIdle as an IE may mean alist of measResultIdle as an IE individually configured for one or moreneighboring inter-frequency carriers by the UE 2 g-01 in the RRC idlemode. A UE according to an embodiment of the disclosure may configuremeasResultIdle for each neighboring inter-frequency carrier whentransmitting the UEInformationResponse message, by using at least one ofthe following methods.

Method 1: The measResultIdle may optionally include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle optionally includes the measurement result        (measResultServingCell) of a serving cell, because there exist        only one serving cell of the UE in the RRC idle mode and        accordingly there is no need to report a plurality of        neighboring inter-frequencies. For example, when        measResultServingCell for each neighboring inter-frequency        carrier is represented in the form of a value of 0 or 1 (or        FALSE or TURE) and is 0 (or FALSE), the measResultIdle may not        include measResultServingCell.    -   When the measResultIdle includes measResultServingCell for each        neighboring inter-frequency carrier, the measResultIdle may        include the same serving cell measurement results.    -   The measResultServingCell may include or may not include at        least one of the following result values.    -   RSRP result values (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   When there are no measurement results of neighboring cells for        all neighboring inter-frequency carriers, the measResultListIdle        may not be included in the UEInformationResponse message.

Method 2: The measResultIdle may always include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle always includes a serving cell measure result        for each neighboring inter-frequency carrier, and the serving        cell measurement results are the same as each other. When there        is no measurement result of neighboring cells for each        neighboring inter-frequency carrier, the measResultListIdle does        not include the neighboring inter-frequency carrier. When there        are no measurement results of neighboring cells for all        neighboring inter-frequency carriers, the measResultListIdle may        not be included in the UEInformationResponse message.    -   The measResultServingCell may include at least one of the        following result values.    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)

When the measResultListIdle is included in the UEInformationResponsemessage in operation 2 g-60, the eNB/gNB 2 g-02 may perform an RRCconnection reconfiguration procedure with the UE 2 g-01. First, theeNB/gNB 2 g-02 may transmit an RRCReconfiguration message to the UE 2g-01 (operation 2 g-65). The RRCReconfiguration message may include atleast one of configuration information about a DRB to process user data,configuration information about SRB1 and/or SRB2 via which a controlmessage may be transmitted and received, or measurement configurationinformation (measConfig). In response to the RRCReconfiguration message,the UE 2 g-01 may apply the information included in theRRCReconfiguration message, and then may transmit anRRCReconfigurationComplete message to the eNB/gNB 2 g-02 (operation 2g-70).

The RRCReconfiguration message in operation 2 g-65 may include a commonconfiguration parameter for configuration of several SCells (Scell Groupconfiguration) at one time or a configuration parameter (SCellconfiguration) for each of the SCells. When the RRCReconfigurationmessage includes a common configuration parameter for several SCells, atleast one of the following methods may be applied.

Method 1: The RRCReconfiguration message may include a common parameterfor each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCReconfiguration message may include SCell group identifiers        for identifying the SCell groups.    -   The RRCReconfiguration message may include a common parameter        for each SCell group (for example, sCellConfigCommon or        sCellGroupCommonConfig).    -   The RRCReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

Method 2: The RRCReconfiguration message may include a common parameterfor each SCell group and different parameters for different SCells ineach SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCReconfiguration message may include SCell group identifiers        for identifying the SCell groups.    -   The RRCReconfiguration message may include a common parameter        for each SCell group (for example, sCellConfigCommon or        sCellGroupCommonConfig).    -   The RRCReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCConnectionReconfiguration message may include an        indicator for indicating delta configuration to apply different        parameters for different SCells in each SCell group. When the        indicator is included in a specific Scell, a common parameter of        an Scell group to which SCells belong. When the indicator is not        included in the specific Scell, only parameters different from        the common parameter of the Scell group may be additionally        included or only the parameter of the specific Scell may be        included.    -   The RRCReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

The eNB/gNB 2 g-02 may apply CA by indicating a state (activated,dormant, or deactivated state) of each SCell configured in the UE 2 g-01by using a MAC CE (operation 2 g-75).

FIG. 2H illustrates a diagram for describing a procedure in which a UEsupporting an idle mode measurement releases an RRC connection with aneNB/gNB and switches an RRC connected mode to an RRC inactive mode, anda method in which the eNB/gNB provides idle mode measurementconfiguration information to the UE, according to an embodiment of thedisclosure.

The UE according to an embodiment of the disclosure may perform a cellselection procedure and/or a cell reselection procedure via frequencymeasurement in order to search for a cell to be camped on or a servingcell in an RRC inactive mode. The UE may separately measure severalfrequencies in the RRC inactive mode and may store results of themeasurements. An idle mode measurement according to an embodiment of thedisclosure may mean that the UE performs measurement in the RRC inactivemode. To this end, the eNB/gNB may transmit, to the UE in the RRCconnected mode, an RRCRelease message including measurementconfiguration information (measIdleConfig) that is available in the RRCinactive mode by the UE. Alternatively, the eNB/gNB may broadcast, tothe UE in the RRC inactive mode, system information (e.g., SIB5 or a newSIBx) including measurement configuration information(measIdleConfigSIB) that is available in the RRC inactive mode by theUE. The UE in the RRC inactive mode may measure at least one frequency,based on the measurement configuration information included in theRRCRelease message or the system information. When the eNB/gNB transmitsa UEInformationRequest message to the UE that has transited from the RRCinactive mode to the RRC connected mode in order to request ameasurement result, the UE may transmit to the eNB/gNB aUEInformationResponse message including a result of a measurementperformed in the RRC inactive mode. This may delay application ofexisting CA by a long time.

Referring to FIG. 2H, a UE 2 h-01 may establish an RRC connection withan eNB/gNB 2 h-02 and thus may be in the RRC connected mode (operation 2h-05). When the UE 2 h-01 that transmits or receives data in the RRCconnected mode does not transmit or receive data for a certain reason orfor a certain time, the eNB/gNB 2 h-02 may transmit an RRCReleasemessage including suspended configuration information (suspendConfig) tothe UE 2 h-01 such that the UE 2 h-01 switches to the RRC inactive mode(operation 2 h-10). The RRCRelease message may further includemeasurement configuration information available in the RRC inactive mode(measIdleConfig). The measIdleConfig being an IE may include at leastone of the following parameters.

-   -   A carrier frequency list used for measurement by a UE in the RRC        inactive mode (measIdleCarrierList) The measIdleCarrier List may        include one or more pieces of information (measIdleCarrier)        about each carrier frequency.    -   Each measIdleCarrier include at least one of the following        pieces of information. Embodiments of the disclosure are not        limited to the following example.    -   dl-CarrierFreq: An absolute radio frequency channel number value        (ARFCN-Value) representing the center frequency of a        synchronization signal block (hereinafter, an SS Block) of        neighboring cells may be included. The UE 2 h-01 may apply        reference signal measurement timing configuration of neighboring        cells, based on the information dl-CarrierFreq, or may perform        neighboring cell measurement.    -   nrofSS-BlocksToAverage: The number of SS/PBCH blocks that are        used to derive a cell measurement value. The UE 2 h-01 may        derive a cell measurement value by taking an average of SS/PBCH        measurement values by applying the signaled value. When the        information nrofSS-BlocksToAverage is not signaled, the UE 2        h-01 may derive a cell measurement value, based on a SS/PBCH        block providing a greatest signal intensity.    -   absThreshSS-BlocsConsolidation: A threshold that is used to        consolidate cell measurement values respectively derived from        SS/PBCH blocks. The UE 2 h-01 may use, in the cell measurement        value, an SS/PBCH block signal intensity that is greater than a        signaled absThreshSS-BlocsConsolidation value. When the        information absThreshSS-BlocsConsolidation is not signaled, the        UE 2 h-01 may derive a cell measurement value, based on a        SS/PBCH block providing a greatest signal intensity.    -   smtc: Measurement timing configuration information for        inter-frequency measurement or intra-frequency measurement may        be included. In detail, the information smtc may mean period and        offset information of a measurement time interval for receiving        an SS/PBCH block, and duration information of the measurement        time interval. An ASN. 1 structure of smtc is as shown in Table        2 below.

TABLE 2 SSB-MTC information element ASN1START TAG-SSB-MTC-START SSB-MTC::= SEQUENCE { periodicityAndOffset CHOICE { sf5 INTEGER (0..4), sf10INTEGER (0..9), sf20 INTEGER (0..19), sf40 INTEGER (0..39), sf80 INTEGER(0..79), sf160 INTEGER (0..159) }, duration  ENUMERATED { sf1, sf2, sf3,sf4, sf5 } }

The UE 2 h-01 may set a reference signal measurement timing via thesignaled value.

-   -   ssbSubcarrierSpacing: A sub-carrier spacing between SSBs may be        included. For example, in the case of a frequency band that is        less than 6 GHz, a 15 or 30 kHz value may be signaled, and, in        the case of a frequency band that is greater than 6 GHz, a 120        or 240 kHz value may be signaled.    -   deriveSSB-IndexFromCell: An indicating value indicating timing        information that the UE 2 h-01 may/should use to derive the        index of an SS block that is transmitted by a neighboring cell        or serving cell existing in a signaled center frequency may be        included. For example, when a deriveSSB-IndexFromCell value is        signaled or set as TRUE, the UE 2 h-01 may derive the index of        an SS block of all of the neighboring cells existing in the        center frequency by applying timing information of any cell        detected in the center frequency. This may also be equally        applied to a case where the center frequency is a serving        frequency, Because, due to a cell reselection procedure, the        center frequency of the UE 2 h-01 performing idle mode        measurement may be a serving frequency or an inter-frequency.        Alternatively, the UE 2 h-01 may apply an SFN and a frame        boundary alignment to all of the cells existing in the center        frequency.    -   reportQuantities: An indicator indicating whether the UE 2 h-01        reports result values of cells measured through idle mode        measurement with the RSRP or the RSRQ or with both of the RSRP        and the RSRQ may be included.    -   reportQuantityCell: The result values of the cells measured by        the UE 2 h-01 through idle mode measurement may be included. In        this case, the UE 2 h-01 may report, to the eNB/gNB 2 h-02, the        result values of the cells measured by the UE 2 h-01 through        idle mode measurement with the RSRP or the RSRQ or with both of        the RSRP and the RSRQ.    -   reportQuantityRsIndexes: An indicator indicating whether the UE        2 h-01 reports information measured for each RS index through        idle mode measurement with the RSRP or the RSRQ or with both of        the RSRP and the RSRQ may be included. The information        reportQuantityRsIndexes may be indicated when a beam level        management is efficient during Scell configuration.    -   maxNrofRS-IndexesToReport: A value representing how many RS        indexes at maximum the UE 2 h-01 reports to the eNB/gNB 2 h-02,        based on idle mode measurement, may be included. The information        maxNrofRS-IndexesToReport may be indicated when a beam level        management is efficient during Scell configuration.    -   includeBeamMeasurements: An indicator indicating that a beam        measurement result is to be included may be included. For        example, when reportQuantityRS-Indexes is set as TRUE for each        SS/PBCH block index, the UE 2 h-01 may report a measurement        value to the eNB/gNB 2 h-02, based on SS/PBCH. The information        includeBeamMeasurements may be indicated when a beam level        management is efficient during Scell configuration.    -   validityArea: A cell list on which the UE 2 h-01 is requested to        perform idle mode measurement and report a result of the idle        mode measurement may be included.    -   measCellList: A cell list on which the UE 2 h-01 is requested to        perform idle mode measurement and report a result of the idle        mode measurement may be included.    -   quantityThreshold: A threshold of the RSRP or RSRQ based on        which the UE 2 h-01 may determine whether to report cells        measured via idle mode measurement may be included.        Alternatively, respective thresholds may be included for the        RSRP and RSRQ.    -   measIdleCarrierList may be signaled for each radio access        technology. For example, measIdleCarrierList may include        measIdleCarrierListEUTRA and measIdleCarrierListNR.    -   A value representing a duration while the UE performs        measurement in the RRC inactive mode (measIdleDuration)

According to an embodiment, the measIdleDuration may represent a timerT311 value or a new timer T3xx value.

The UE may perform idle mode measurement after the UE receives theRRCRelease message and before the measIdleDuration expires.

-   -   measIdleDuration may be signaled for each radio access        technology or regardless of radio access technologies. For        example, measIdleDuration may be divided into        measIdleDurationEUTRA and measIdleDurationNR and signaled, or        may be signaled as a single value to be commonly applied.

When the RRCRelease message includes measIdleConfig in operation 2 h-10,the UE 2 h-01 may delete VarMeasIdleConfig and VarMeasIdleReport beingUE variables. The UE may store, in the measIdleConfig, the valuerepresenting the duration while the UE performs measurement in the RRCinactive mode (e.g., measIdleDuration), and may drive a timer byapplying the value representing the duration while the UE performsmeasurement in the RRC inactive mode. When the RRCRelease messageincludes the carrier frequency list used for measurement by the UE inthe RRC inactive mode, the UE 2 h-01 may store the carrier frequencylist and perform idle mode measurement while a timer is operating insupportable carriers, based on the stored carrier frequency list(operation 2 h-16). When the RRCRelease message does not include thecarrier frequency list used for measurement by the UE in the RRCinactive mode, the UE 2 h-01 may receive system information by searchingfor and camping on a suitable cell, via a cell selection procedureand/or a cell reselection procedure (operation 2 h-15). When a carrierfrequency list measIdleConfigSIB used for measurement in the RRCinactive mode is included in the received system information, the UE 2h-01 may store the received measIdleConfigSIB while the on-goingoperation of the timer continues, or may replace the carrier frequencylist within the UE 2 h-01, based on the received measIdleConfigSIB, andperform idle mode measurement while the timer is operating insupportable carriers, based on the carrier frequency list (operation 2h-15). The measIdleConfigSIB according to an embodiment may include someor all of the parameters included in the above-described measIdleConfig.

When system information that is broadcast by a target cell does notinclude the measIdleConfigSIB through a cell reselection procedure, theUE 2 h-01 may stop the on-going idle mode measurement.

In operation 2 h-16, the UE 2 h-01 may perform measurement by deriving atiming of an SS/PBCH block, based on an SFN and a subframe of a certaincell, by using the smtc received from the eNB/gNB 2 h-02 and a certainequation. The certain equation is expressed as follows. SMTC issubstituted into the equation below. An SFN including a measurement timeinterval of each SS/PBCH block satisfies the following equation.SFN mod T=(FLOOR(Offset/10))

When a period is greater than 5 subframes, a subframe by which a firstSS/PBCH block of the interval satisfies the following equation.subframe=Offset mod 10Otherwise,subframe=Offset or (Offset+5)

Herein, T means CEIL(Periodicity/10).

A UE according to an embodiment of the disclosure may measure aplurality of frequencies in the RRC inactive mode and may store resultsof the measurements. In this case, a serving cell or neighboring cellsmay have different SFNs and different subframe timings. Thus, the UE 2h-01 needs to determine the SFNs and the subframes of which serving cellor neighboring cells are based on to derive the timing of the SS/PBCHblock. According to the disclosure, the serving cell or neighboringcells serving as a basis are determined using at least one of thefollowing methods. Embodiments of the disclosure are not limited to thefollowing examples.

Option 1) When the RRCRelease message (operation 2 h-10) includes smtc,the UE may derive the timing of the SS/PBCH block for a cell that hasreceived the RRCRelease message, based on the smtc information. On theindicated dl-CarrierFreq in the RRCRelease message, the UE shall notconsider SS/PBCH block transmission in subframes outside the SMTCoccasion for RRMs based on SS/PBCH blocks.

Option 2) When the RRCRelease message (operation 2 h-10) includes smtc,the UE may derive the timing of the SS/PBCH block for a serving cell,based on the smtc information. On the indicated dl-CarrierFreq in theRRCRelease message, the UE shall not consider SS/PBCH block transmissionin subframes outside the SMTC occasion for RRMs based on SS/PBCH blocks.

Option 3) When the RRCRelease message (operation 2 h-10) includes smtc,the UE may derive the timing of the SS/PBCH block for a cell list(measCellList or validityArea) included in the RRCRelease message, basedon the smtc information. On the indicated dl-CarrierFreq in theRRCRelease message, the UE shall not consider SS/PBCH block transmissionin subframes outside the SMTC occasion for RRMs based on SS/PBCH blocks.

Option 4) When the system information (operation 2 h-15) includes smtc,the UE may derive the timing of the SS/PBCH block for a cell list(measCellList or validityArea) included in the system information, basedon the smtc information. For example, for a cell included in a servingfrequency, the UE may apply smtc information included in SIB2, or, for acell included in an inter-frequency, the UE may apply smtc informationincluded in SIB4. On the indicated dl-CarrierFreq in the RRCReleasemessage, the UE shall not consider SS/PBCH block transmission insubframes outside the SMTC occasion for RRMs based on SS/PBCH blocks.

The UE may receive an SS/PBCH block during the derived measurement timeinterval, and may perform RSRP, RSRQ, etc. corresponding to the receivedSS/PBCH block.

The UE 2 h-01 may perform a random access procedure in order toestablish an RRC connection with the eNB/gNB 2 h-02. When random accessis triggered (operation 2 h-18), the UE 2 h-01 may select a PRACHoccasion and transmit a Random Access Preamble to the eNB/gNB 2 h-02(operation 2 h-20). In response to the Random Access Preamble, theeNB/gNB 2 h-02 may transmit an RAR message to the UE 2 h-01 (operation 2h-25). The UE 2 h-01 in the RRC idle mode may establish an inversedirection transmission synchronization with the eNB/gNB 2 h-02 throughoperations 2 h-20 and 2 h-25.

The UE 2 h-01 in the RRC idle mode may perform an RRC connection resumeprocedure with the eNB/gNB 2 h-02. First, the UE 2 h-01 may transmit anRRCResumeRequest message or an RRCResumeRequest1 message to the eNB/gNB2 h-02 (operation 2 h-30). The RRCResumeRequest message or theRRCResumeRequest1 message may include, for example, a UE identifier(resumeIdentity), resume encryption information (resumeMAC-I), and acause (resumeCause) for resuming an RRC connection, which are used by aneNB/gNB to retrieve a terminal context. In response to theRRCResumeRequest message or the RRCResumeRequest1 message, the eNB/gNB 2h-02 may transmit an RRCResume message to the UE 2 h-01 (operation 2h-35). The RRCResume message may include radio bearer configurationinformation (radioBearerConfig), master cell group configurationinformation (masterCellGroup), measurement configuration information(measConfig), etc. In detail, the radio bearer configuration informationand the master cell group configuration information may includeconfiguration information of an SRB and DRBs that resume, RLC bearerconfiguration information about the SRB and the DRBs, MAC cell groupconfiguration information (mac-CellGroupConfig), physical cell groupconfiguration information (physicalCellGroupConfig), etc. In response tothe RRCSetup message, the UE 2 h-01 may apply the information and mayswitch to the RRC connected mode (operation 2 h-36). When the systeminformation received in operation 2 h-15 includes an indicator(idleModeMeasurements) indicating that the eNB/gNB 2 h-02 is able toprocess idle mode measurement of the UE 2 h-01, and theVarMeasIdleReport as a UE variable includes idle mode measurementinformation by performing idle mode measurement in operation 2 h-16, theUE 2 h-01 switched to the RRC connected mode may include, in anRRCResumeComplete message, an indicator (idleMeasAvailable) indicatingthat an idle mode measurement report is possible. The UE 2 h-01 may stopwhen the timer (for example, T311 or T3xx) keeps operating. The UE 2h-01 in the RRC connected mode may transmit the RRCResumeCompletemessage to the eNB/gNB 2 h-02 through SRB1 (operation 2 h-40).

When the RRC connection resume procedure is successfully performed, theeNB/gNB 2 h-02 may perform an RRC connection reconfiguration procedurewith the UE 2 h-01. First, the eNB/gNB 2 h-02 may transmit anRRCReconfiguration message to the UE 2 h-01 (operation 2 h-45). TheRRCReconfiguration message may include at least one of radio bearerconfiguration information (radioBearerConfig), master cell groupconfiguration information (masterCellGroup), or measurementconfiguration information (measConfig). In response to theRRCReconfiguration message, the UE 2 h-01 may apply the informationincluded in the RRCReconfiguration message, and then may transmit anRRCReconfigurationComplete message to the eNB/gNB 2 h-02 (operation 2h-50).

When the RRCResumeComplete message includes the indicator(idleMeasAvailable) indicating that an idle mode measurement report ispossible, in operation 2 h-40, the eNB/gNB 2 h-02 may perform a UEinformation procedure with the UE 2 h-01. The UE information proceduremay be immediately performed without performing the above-described RRCconnection reconfiguration procedure (including operations 2 h-45 and 2h-50). The eNB/gNB 2 h-02 may transmit, to the UE 2 h-01 in the RRCconnected mode, a UEInformationRequest message including an indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC inactive mode (operation 2 h-55). When security issuccessfully configured, the UE 2 h-01 that has received theUEInformationRequest message may perform the following processes.

1> When the UEInformationRequest message includes the indicator(idleModeMeasurementReq) requesting a result of the measurementperformed in the RRC inactive mode and the UE 2 h-01 has stored theVarMeasIdleReport,

2> measResultListIdle included in a UEInformationResponse message is setas a measReportIdle value (or an idleMeasReport value) included in theVarMeasIdleReport.

2> When it is confirmed by lower layers that the UEInformationResponsemessage was transmitted successfully, the VarMeasIdleReport isdiscarded.

1> The UEInformationResponse message is submitted to the lower layersvia the SRB1. The UE 2 h-01 may transmit, to the eNB/gNB 2 h-02, theUEInformationReponse message including a list (measResultListIdle) ofresults of the measurements performed in the RRC inactive mode(operation 2 h-60).

In the above description, the measResultListIdle as an IE may mean alist of measResultIdle as an IE individually configured for one or moreneighboring inter-frequency carriers by the UE 2 h-01 in the RRCinactive mode. A UE according to an embodiment of the disclosure mayconfigure measResultIdle for each neighboring inter-frequency carrierwhen transmitting the UEInformationResponse message, by using at leastone of the following methods.

Method 1: The measResultIdle may optionally include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle optionally includes the measurement result        (measResultServingCell) of a serving cell, because there exist        only one serving cell of the UE in the RRC inactive mode and        accordingly there is no need to report a plurality of        neighboring inter-frequencies. For example, when        measResultServingCell for each neighboring inter-frequency        carrier is represented in the form of a value of 0 or 1 (or        FALSE or TURE) and is 0 (or FALSE), the measResultIdle may not        include measResultServingCell.    -   When the measResultIdle includes measResultServingCell for each        neighboring inter-frequency carrier, the measResultIdle may        include the same serving cell measurement results.    -   The measResultServingCell may include or may not include at        least one of the following result values.    -   RSRP result values (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   When there are no measurement results of neighboring cells for        all neighboring inter-frequency carriers, the measResultListIdle        may not be included in the UEInformationResponse message.

Method 2: The measResultIdle may always include a measurement result(measResultServingCell) of a serving cell through idle mode measurementwith respect to each neighboring inter-frequency carrier, and mayoptionally include a measurement result (measResultNeighCells) of one ormore neighboring cells.

-   -   The measResultIdle always includes a serving cell measure result        for each neighboring inter-frequency carrier, and the serving        cell measurement results are the same as each other. When there        is no measurement result of neighboring cells for each        neighboring inter-frequency carrier, the measResultListIdle does        not include the neighboring inter-frequency carrier. When there        are no measurement results of neighboring cells for all        neighboring inter-frequency carriers, the measResultListIdle may        not be included in the UEInformationResponse message.    -   The measResultServingCell may include at least one of the        following result values.    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)    -   A measurement result of neighboring cells for each neighboring        inter-frequency carrier may include at least one of the        following parameters.    -   A carrier frequency (CarrierFreq) containing an ARFCN-Value    -   A physical cell identifier (phyCellId) of each neighboring cell    -   RSRP result value (rsrpResult)    -   RSRQ result value (rsrqResult)

When the measResultListIdle is included in the UEInformationResponsemessage in operation 2 h-60, the eNB/gNB 2 h-02 may perform an RRCconnection reconfiguration procedure with the UE 2 h-01. First, theeNB/gNB 2 h-02 may transmit an RRCReconfiguration message to the UE 2h-01 (operation 2 h-65). The RRCReconfiguration message may include atleast one of configuration information about a DRB to process user data,configuration information about SRB1 and/or SRB2 via which a controlmessage may be transmitted and received, or measurement configurationinformation (measConfig). In response to the RRCReconfiguration message,the UE 2 h-01 may apply the information included in theRRCReconfiguration message, and then may transmit anRRCReconfigurationComplete message to the eNB/gNB 2 h-02 (operation 2h-70).

The RRCReconfiguration message in operation 2 h-65 may include a commonconfiguration parameter for configuration of several SCells (Scell Groupconfiguration) at one time or a configuration parameter (SCellconfiguration) for each of the SCells. When the RRCReconfigurationmessage includes a common configuration parameter for several SCells, atleast one of the following methods may be applied.

Method 1: The RRCReconfiguration message may include a common parameterfor each SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCReconfiguration message may include SCell group identifiers        for identifying the SCell groups.    -   The RRCReconfiguration message may include a common parameter        for each SCell group (for example, sCellConfigCommon or        sCellGroupCommonConfig).    -   The RRCReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

Method 2: The RRCReconfiguration message may include a common parameterfor each SCell group and different parameters for different SCells ineach SCell group (for example, SCellGroupToAddModList orSCellGroupToReleaseList).

-   -   Because a plurality of SCell groups may exist, the        RRCReconfiguration message may include SCell group identifiers        for identifying the SCell groups.    -   The RRCReconfiguration message may include a common parameter        for each SCell group (for example, sCellConfigCommon or        sCellGroupCommonConfig).    -   The RRCReconfiguration message may include a list        (sCellToAddModList) for adding or modifying one or more cells to        each SCell group. In this case, an initial state of each Scell        may be set as an activated state, a dormant state, or an        inactive state.    -   The RRCReconfiguration message may include an indicator for        indicating delta configuration to apply different parameters for        different SCells in each SCell group. When the indicator is        included in a specific Scell, a common parameter of an Scell        group to which SCells belong. When the indicator is not included        in the specific Scell, only parameters different from the common        parameter of the Scell group may be additionally included or        only the parameter of the specific Scell may be included.    -   The RRCReconfiguration message may include a list        (sCellToReleaseList) for releasing one or more cells from each        SCell group.

The eNB/gNB 2 h-02 may apply CA by indicating a state (activated,dormant, or deactivated state) of each SCell configured in the UE 2 h-01by using a MAC CE (operation 2 h-75).

FIG. 2I illustrates a block diagram of a structure of a UE according toan embodiment of the disclosure.

Referring to FIG. 2I, the UE may include an RF processor 2 i-10, abaseband processor 2 i-20, a storage 2 i-30, and a controller 2 i-40.Embodiments are not limited thereto, and the UI may include more or lesscomponents than those illustrated in FIG. 2I. The UE of FIG. 2I maycorrespond to the UE of FIG. 1I.

According to an embodiment of the disclosure, the RF processor 2 i-10may perform functions for transmitting and receiving a signal via aradio channel, such as a band conversion, amplification, and the like ofthe signal. In other words, the RF processor 2 i-10 may up-convert abaseband signal provided from the baseband processor 2 i-20, to an RFband signal and transmit the RF band signal through an antenna, anddown-convert an RF band signal received through an antenna, to abaseband signal. For example, the RF processor 2 i-10 may include atransmit filter, a receive filter, an amplifier, a mixer, an oscillator,a DAC, and an ADC. Although only a single antenna is illustrated in FIG.2I, the UE may include multiple antennas.

The RF processor 2 i-10 may include a plurality of RF chains. The RFprocessor 2 i-10 may perform beamforming. For beamforming, the RFprocessor 2 i-10 may adjust phases and amplitudes of signals transmittedor received through multiple antennas or antenna elements. The RFprocessor 2 i-10 may perform an MIMO operation and may receive layers(or data of multiple layers) in the MIMO operation. The RF processor 2i-10 may perform received beam sweeping by appropriately configuringmultiple antennas or antenna elements, or may adjust a direction and abeam width of the received beam such that the received beam coordinateswith a transmit beam, under the control of the controller 2 i-40.

The baseband processor 2 i-20 may perform conversion between a basebandsignal and a bitstream based on physical layer specifications of asystem. For example, for data transmission, the baseband processor 2i-20 may generate complex symbols by encoding and modulating a transmitbitstream. For data reception, the baseband processor 2 i-20 mayreconstruct a received bitstream by demodulating and decoding a basebandsignal provided by the RF processor 2 i-10. For example, according to anOFDM scheme, for data transmission, the baseband processor 2 i-20 maygenerate complex symbols by encoding and modulating a transmitbitstream, map the complex symbols to subcarriers, and then configureOFDM symbols by performing IFFT and CP insertion. For data reception,the baseband processor 2 i-20 may split a baseband signal provided fromthe RF processor 2 i-10, in OFDM symbol units, reconstruct signalsmapped to subcarriers by performing FFT, and then reconstruct a receivedbitstream by demodulating and decoding the signals.

The baseband processor 2 i-20 and the RF processor 2 i-10 may transmitand receive signals as described above. Each of the baseband processor 2i-20 and the RF processor 2 i-10 may also be called a transmitter, areceiver, a transceiver, or a communicator. At least one of the basebandprocessor 2 i-20 or the RF processor 2 i-10 may include multiplecommunication modules to support multiple different radio accesstechnologies. Also, at least one of the baseband processor 2 i-20 or theRF processor 2 i-10 may include multiple different communication modulesto process signals of different frequency bands. For example, thedifferent radio access technologies may include an LTE network, an NRnetwork, etc. The different frequency bands may include an SHF (e.g.,2.5 GHz and 5 GHz) band and a mmWave (e.g., 60 GHz) band. The UE maytransmit or receive a signal to or from a base station by using thebaseband processor 2 i-20 and the RF processor 2 i-10, and the signalmay include control information and data.

The storage 2 i-30 may store data for operations of the UE, e.g., basicprograms, application programs, and configuration information Thestorage 2 i-30 may provide the stored data upon request by thecontroller 2 i-40. The storage 2 i-30 may be composed of storage media,such as ROM, RAM, hard disks, CD-ROM, and DVDs, or a combination of thestorage media. The storage 2 i-30 may be composed of a plurality ofmemories.

The controller 2 i-40 may control overall operations of the UE. Forexample, the controller 2 i-40 may transmit and receive signals throughthe baseband processor 2 i-20 and the RF processor 2 i-10. Thecontroller 2 i-40 may write and read data to and from the storage 2i-30. To this end, the controller 2 i-40 may include at least oneprocessor. For example, the controller 2 i-40 may include a CPperforming control for communication, and an AP controlling an upperlayer, such as an application program. The controller 2 i-40 may controlthe UE to perform a communication method for supporting theabove-described carrier aggregation. At least one of the componentsincluded in the UE may be implemented by using a single chip.

FIG. 2J illustrates a block diagram of a structure of a base stationaccording to an embodiment of the disclosure.

The base station according to an embodiment of the disclosure mayinclude at least one TRP. Referring to FIG. 2J, the base station mayinclude an RF processor 2 j-10, a baseband processor 2 j-20, acommunicator 2 j-30, a storage 2 j-40, and a controller 2 j-50.Embodiments are not limited thereto, and the base station may includemore or less components than those illustrated in FIG. 2J. The basestation of FIG. 2J may correspond to the base station of FIG. 2I.

The RF processor 2 j-10 may perform functions for transmitting andreceiving a signal via a radio channel, such as a band conversion,amplification, and the like of the signal. In other words, the RFprocessor 2 j-10 may up-convert a baseband signal provided from thebaseband processor 2 i-20, to an RF band signal and transmit the RF bandsignal through an antenna, and down-convert an RF band signal receivedthrough an antenna, to a baseband signal. For example, the RF processor2 j-10 may include a transmitting filter, a receiving filter, anamplifier, a mixer, an oscillator, a DAC, an ADC, or the like. Althoughonly a single antenna is illustrated in FIG. 2J, the RF processor 2 j-10may include multiple antennas. The RF processor 2 j-10 may include aplurality of RF chains. The RF processor 2 j-10 may perform beamforming.For beamforming, the RF processor 2 j-10 may adjust phases andamplitudes of signals transmitted or received through multiple antennasor antenna elements. The RF processor 2 j-10 may perform a DL MIMOoperation by transmitting at least one layer.

The baseband processor 2 j-20 may perform conversion between a basebandsignal and a bitstream based on physical layer specifications of a firstradio access technology. For example, for data transmission, thebaseband processor 2 j-20 may generate complex symbols by encoding andmodulating a transmit bitstream. For data reception, the basebandprocessor 2 j-20 may reconstruct a received bitstream by demodulatingand decoding a baseband signal provided by the RF processor 2 j-10. Forexample, according to an OFDM scheme, for data transmission, thebaseband processor 2 j-20 may generate complex symbols by encoding andmodulating a transmit bitstream, map the complex symbols to subcarriers,and then configure OFDM symbols by performing IFFT and CP insertion. Fordata reception, the baseband processor 2 j-20 may split a basebandsignal provided from the RF processor 2 j-10, in OFDM symbol units,reconstruct signals mapped to subcarriers by performing FFT, and thenreconstruct a received bitstream by demodulating and decoding thesignals. The baseband processor 2 j-20 and the RF processor 2 j-10 maytransmit and receive signals as described above. Accordingly, each ofthe baseband processor 2 j-20 and the RF processor 2 j-10 may also becalled a transmitter, a receiver, a transceiver, a communicator, or awireless communicator. The base station may transmit or receive a signalto or from a base station by using the baseband processor 2 j-20 and theRF processor 2 j-10, and the signal may include control information anddata.

The communicator 2 j-30 may provide an interface for communicating withother nodes in a network. According to an embodiment, the communicator 2j-30 may be a backhaul communicator.

The storage 2 j-40 may store data for operations of a main base station,e.g., basic programs, application programs, and configurationinformation In particular, the storage 2 j-40 may store informationabout bearers allocated for a connected UE, a measurement reporttransmitted from the connected UE, etc. The storage 2 j-40 may storecriteria information used to determine whether to provide or releasemulti-connectivity to or from the UE. The storage 2 j-40 may provide thestored data upon request by the controller 2 j-50. The storage 2 j-40may be composed of storage media, such as ROM, RAM, hard disks, CD-ROM,and DVDs, or a combination of the storage media. The storage 2 j-40 maybe composed of a plurality of memories.

The controller 2 j-50 may control overall operations of the basestation. For example, the controller 2 j-50 may transmit and receivesignals through the baseband processor 2 j-20 and the RF processor 2j-10 or through the communicator 2 j-30. The controller 2 j-50 may writeand read data to and from the storage 2 j-40. To this end, thecontroller 2 j-50 may include at least one processor. Each of thebaseband processor 2 j-20 and the RF processor 2 j-10 may also be calleda transmitter, a receiver, a transceiver, a communicator, or a wirelesscommunicator. The controller 2 j-50 may control the base station toperform a communication method for supporting the above-describedcarrier aggregation. At least one of the components included in the basestation may be implemented by using a single chip.

The methods according to embodiments of the disclosure as described inthe specification or in the following claims may be implemented ashardware, software, or a combination of hardware and software. Whenimplemented as software, a computer-readable storage medium storing oneor more programs (e.g., software modules) may be provided. The one ormore programs stored in the computer-readable storage medium areconfigured for execution by one or more processors in an electronicdevice. The one or more programs include instructions directing theelectronic device to execute the methods according to embodiments of thedisclosure as described the specification or in the following claims.

The programs (e.g., software modules or software) may be stored innon-volatile memory (including random access memory (RAM) or flashmemory), read only memory (ROM), electrically erasable programmable readonly memory (EEPROM), a magnetic disc storage device, a compact disc(CD)-ROM, a digital versatile disc (DVD), another optical storagedevice, or a magnetic cassette. Alternatively, the programs may bestored in memory including a combination of some or all of theabove-mentioned storage media. A plurality of such memories may beincluded.

In addition, the programs may be stored in an attachable storage deviceaccessible through any or a combination of communication networks suchas Internet, an intranet, a local area network (LAN), a wide LAN (WLAN),and a storage area network (SAN). Such a storage device may access theelectronic device performing the embodiments of the disclosure via anexternal port. Furthermore, a separate storage device on thecommunication network may access a device performing the embodiments ofthe disclosure.

According to the above-described embodiments, CA may be effectivelyprovided in a mobile communication system.

In the above-described embodiments of the disclosure, the elementsincluded in the disclosure are expressed in a singular or plural formaccording to the proposed specific embodiment of the disclosure.However, the singular or plural expression is appropriately selected forease of description according to the presented situation, and thedisclosure is not limited to a single element or plural elements. Thoseelements described in a plural form may be configured as a singleelement, and those elements described in a singular form may beconfigured as plural elements.

The embodiments of the disclosure disclosed in the specification anddrawings are merely presented specific examples to easily explain thetechnical contents of the disclosure and promote understanding of thedisclosure, and are not intended to limit the scope of the disclosure.In other words, it is obvious to those skilled in the art that othermodifications based on the technical spirit of the disclosure can beimplemented. In addition, each of the above embodiments can be combinedwith each other when necessary to operate. For example, portions of oneembodiment of the disclosure and another embodiment may be combined witheach other so that a base station and a UE may be operated. Furthermore,embodiments of the disclosure may be applicable to other communicationsystems, and other modifications based on the technical spirit of theembodiments may be implemented.

Although the present disclosure has been described with variousembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method performed by a user equipment (UE), themethod comprising: receiving a message including measIdleConfig;performing measurement in an idle mode or an inactive mode, based on themeasIdleConfig; receiving a UEInformationRequest message for requestinga result of the measurement; and transmitting a UEInformationResponsemessage including the result of the measurement, wherein the messageincludes a radio resource control (RRC) release message or systeminformation, wherein the measIdleConfig includesmeasIdleCarrierListEUTRA and measIdleCarrierListNR including informationon at least one measIdleCarrier, wherein the information includesreportQuantities associated with the at least one measIdleCarrier,wherein the measIdleConfig includes an indicator(includeBeamMeasurements) indicating whether to include a beammeasurement result.
 2. The method of claim 1, wherein the result of themeasurement includes a measurement result of a serving cell and a resultof measurement with respect to each of one or more frequency carriers,and the result of the measurement with respect to each of one or morefrequency carriers comprises a measurement result of one or more cells.3. The method of claim 1, wherein the measIdleConfig includes at leastone of an indicator (reportQuantityRsIndexes) indicating whether the UEreports a measurement result for each reference signal (RS) index with areference signal received power (RSRP) or a reference signal receivedquality (RSRQ or with both of the RSRP and the RSRQ, or an indicator(maxNrofRS-IndexesToReport) indicating how many measurement results atmaximum from among the measurement results for the RS indexes the UEreports.
 4. The method of claim 1, wherein the measIdleConfig includesat least one of information (nrofSS-BlocksToAverage) about a number ofsynchronization signal blocks that are used to derive a cell measurementvalue, a threshold (absThreshSS-BlocsConsolidation) that is used toconsolidate measurement values of the synchronization signal blocks,measurement timing configuration information (smtc), a sub-carrierspacing between the synchronization signal blocks(ssbSubcarrierSpacing), or timing information (deriveSSB-IndexFromCell)that is used to determine indexes of the synchronization signal blocks.5. The method of claim 1, wherein the measIdleConfig comprises at leastone of information (measIdleDuration) about a duration while the UEperforms measurement, cell list information (measCellList) of a list ofcells that are to be measured by the UE, or information(quantityThreshold) about a threshold based on which the UE determineswhether to report the result of the measurement.
 6. The method of claim5, further comprising: transmitting an RRCResumeRequest message; andreceiving an RRCConnectionReject message, wherein, when theRRCConnectionReject message includes waitTime, the UE continuouslyperforms measurement in the idle mode until a timer operating accordingto the information (measIdleDuration) expires.
 7. A method performed bya base station, the method comprising: transmitting a message includingmeasIdleConfig; transmitting a UEInformationRequest message forrequesting a result of measurement; and receiving aUEInformationResponse message including the result of the measurement,wherein the includes a radio resource control (RRC) Release message orsystem information, wherein the measIdleConfig includesmeasIdleCarrierListEUTRA and measIdleCarrierListNR including informationon at least one measIdleCarrier, wherein the information includesreportQuantities associated with the at least one measIdleCarrier,wherein the measIdleConfig includes an indicator(includeBeamMeasurements) indicating whether to include a beammeasurement result.
 8. The method of claim 7, wherein the measIdleConfigat least one of an indicator (reportQuantityRsIndexes) indicatingwhether the UE reports a measurement result for each reference signal(RS) index with a reference signal received power (RSRP) or referencesignal received quality (RSRQ), an indicator (maxNrofRS-IndexesToReport)indicating how many measurement results at maximum from among themeasurement results for the RS indexes the UE reports.
 9. The method ofclaim 7, wherein the measIdleConfig includes at least one of information(nrofSS-BlocksToAverage) about a number of synchronization signal blocksthat are used to derive a cell measurement value, a threshold(absThreshSS-BlocsConsolidation) that is used to consolidate measurementvalues of the synchronization signal blocks, measurement timingconfiguration information (smtc), a sub-carrier spacing between thesynchronization signal blocks (ssbSubcarrierSpacing), or timinginformation (deriveSSB-IndexFromCell) that is used to determine indexesof the synchronization signal blocks.
 10. A user equipment (UE) in awireless communication system, the UE comprising: a transceiver; and aprocessor coupled to the transceiver and configured to: receive amessage including measIdleConfig, perform measurement in an idle mode oran inactive mode, based on the measIdleConfig, receive aUEInformationRequest message for requesting a result of the measurement,and transmit a UEInformationResponse message including the result of themeasurement, wherein the message includes a radio resource control (RRC)release message or system information, wherein the measIdleConfigincludes measIdleCarrierListEUTRA and measIdleCarrierListNR includinginformation on at least one measIdleCarrier, wherein the informationincludes reportQuantities associated with the at least onemeasIdleCarrier, wherein the measIdleConfig includes an indicator(includeBeamMeasurements) indicating whether to include a beammeasurement result.
 11. The UE of claim 10, wherein the result of themeasurement includes a measurement result of a serving cell and a resultof measurement with respect to each of one or more frequency carriers,and the result of the measurement with respect to each of one or morefrequency carriers comprises a measurement result of one or more cells.12. The UE of claim 10, wherein the measIdleConfig includes at least oneof an indicator (reportQuantityRsIndexes) indicating whether the UEreports a measurement result for each reference signal (RS) index withRSRP, or an indicator (maxNrofRS-IndexesToReport) indicating how manymeasurement results at maximum from among the measurement results forthe RS indexes the UE reports.
 13. The UE of claim 10, wherein themeasIdleConfig includes at least one of information(nrofSS-BlocksToAverage) about a number of synchronization signal blocksthat are used to derive a cell measurement value, a threshold(absThreshSS-BlocsConsolidation) that is used to consolidate measurementvalues of the synchronization signal blocks, measurement timingconfiguration information (smtc), a sub-carrier spacing between thesynchronization signal blocks (ssbSubcarrierSpacing), or timinginformation (deriveSSB-IndexFromCell) that is used to determine indexesof the synchronization signal blocks.
 14. The UE of claim 10, whereinthe measIdleConfig includes at least one of information(measIdleDuration) about a duration while the UE performs measurement,cell list information (measCellList) of a list of cells that are to bemeasured by the UE, or information (quantityThreshold) about a thresholdbased on which the UE determines whether to report the result of themeasurement.
 15. The UE of claim 14, wherein the processor is furtherconfigured to transmit an RRCResumeRequest message and receive anRRCConnectionReject message, and, when the RRCConnectionReject messageincludes waitTime, the UE continuously performs measurement in the idlemode or the inactive mode until a timer operating according to theinformation (measIdleDuration) expires.
 16. A base station forsupporting idle mode measurement, the base station comprising: atransceiver; and a processor coupled to the transceiver and configuredto: transmit a message including measIdleConfig, transmit aUEInformationRequest message for requesting a result of measurement, andreceive a UEInformationResponse message including the result of themeasurement, wherein the measurement is performed in an idle mode or aninactive mode, wherein the message includes a radio resource control(RRC) Release message or system information wherein the measIdleConfigincludes measIdleCarrierListEUTRA and measIdleCarrierListNR includinginformation on at least one measIdleCarrier, wherein the informationincludes reportQuantities associated with the at least onemeasIdleCarrier, wherein the measIdleConfig includes an indicator(includeBeamMeasurements) indicating whether to include a beammeasurement result.
 17. The base station of claim 16, wherein themeasIdleConfig includes at least one of an indicator(reportQuantityRsIndexes) indicating whether the UE reports ameasurement result for each reference signal (RS) index with a referencesignal received power (RSRP) or a reference signal received quality£RSRQ), an indicator (maxNrofRS-IndexesToReport) indicating how manymeasurement results at maximum from among the measurement results forthe RS indexes the UE reports.
 18. The base station of claim 16, whereinthe measIdleConfig includes at least one of information(nrofSS-BlocksToAverage) about a number of synchronization signal blocksthat are used to derive a cell measurement value, a threshold(absThreshSS-BlocsConsolidation) that is used to consolidate measurementvalues of the synchronization signal blocks, measurement timingconfiguration information (smtc), a sub-carrier spacing between thesynchronization signal blocks (ssbSubcarrierSpacing), or timinginformation (deriveSSB-IndexFromCell) that is used to determine indexesof the synchronization signal blocks.